Questions on Algebra: Matrices, determinant, Cramer rule answered by real tutors!

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Question 175335: How ould yu solve this? I understand the 2x2 matrice but this one is different
no tin the book
Perform the indicated operation, whenever possible
[-9 7] [-5 -1] [-2 -2]
8 -9 + 2 2 - -4 -4
I this problem they have [ for th two lines in each box and then + then [ then minus [
I hope you understand..Cant find the [ bigg enough to do the boxes in each 2x2 matrice..
my answer of choice is:
A. -16 4 B. -12 8 c. -2 10 d. -6 6
6 -11 14 -3 10 -7 2 -15
I hope you understand...I think it is C.
: How ould yu solve this? I understand the 2x2 matrice but this one is different
no tin the book
Perform the indicated operation, whenever possible
[-9 7] [-5 -1] [-2 -2]
8 -9 + 2 2 - -4 -4
I this problem they have [ for th two lines in each box and then + then [ then minus [
I hope you understand..Cant find the [ bigg enough to do the boxes in each 2x2 matrice..
my answer of choice is:
A. -16 4 B. -12 8 c. -2 10 d. -6 6
6 -11 14 -3 10 -7 2 -15
I hope you understand...I think it is C.

Answer by Fombitz(1788) About Me  (Show Source):
You can put this solution on YOUR website!
I think this is your problem.
(matrix(2,2,9,7,8,-9))+(matrix(2,2,-5,-1,2,2))+(matrix(2,2,-2,-2,-4,-4))=<BR>
(matrix(2,2,a,b,c,d))
If not, please let me know.
a=-9-5-2=-16
b=7-1-2=4
c=8+2-4=6
d=-9+2-4=-11
(matrix(2,2,a,b,c,d))=(matrix(2,2,-16,4,6,-11))
The answer is A.

Question 175431: How do I find B-CF?
B= [2,8,.6,3] C=[12,0,1.5,1,-6,7] F=[-2,0,0,8,2,1]
: How do I find B-CF?
B= [2,8,.6,3] C=[12,0,1.5,1,-6,7] F=[-2,0,0,8,2,1]

Answer by Fombitz(1788) About Me  (Show Source):
You can put this solution on YOUR website!
I'm guessing on the make up of the matrices.
First off let's look at [C][F].
[C]=(matrix(2,3,12,0,1.5,1,-6,7))
[F]=(matrix(3,2,-2,0,0,8,2,1))
[C][F]=(matrix(2,2,-21,1.5,12,-41))
where each element of [C][F] comes from multiplying a row of [C] with a column of [F].
Example: First element is product of first row and first column.
CF[1,1]=12*-2+0*0+1.5*2=-24+3=-21
.
.
.
Now that we have [C][F], we can subtract it from [B], element by element,
[B]-[C][F]=(matrix(2,2,2,8,.6,3))-(matrix(2,2,-21,1.5,12,-41))
[B]-[C][F]=(matrix(2,2,23,6.5,-11.4,44))
.
.
.
If this is not how the matrices look,please re-state the problem and be more specific about the make up of the matrices (rows x columns).
Here's an example.
[A] is a 2x2 matrix. A=[1,2,3,4].
The assumption is that [A] looks like this,
[A]=(matrix(2,2,1,2,3,4))
[B] is a 3x2 matrix. B=[5,6,7,8,9,10]
[B]=(matrix(3,2,5,6,7,8,9,10))

Question 175559This question is from textbook algebra 2
: This question is from textbook algebra 2
:
Answer by Mathtut(1329) About Me  (Show Source):
You can put this solution on YOUR website!
need a problem..thanks

Question 175527: How do i find BA?
B= 2 8 A= 3 0
.6 3 2 -1
: How do i find BA?
B= 2 8 A= 3 0
.6 3 2 -1

Answer by Mathtut(1329) About Me  (Show Source):
You can put this solution on YOUR website!
I am going to assume that .6 is a typo and call it 6 it I am right you have your answer if wrong just follow the method and replace it with .6
:
(matrix(2,2,2,8,6,3))(matrix(2,2,3,0,2,-1))
the R1C1 element is found by 2(3)-8(2)=-10
the R1C2 element is found by 2(0)-8(-1)=8
the R2C1 element is found by 6(3)-3(2)=12
the R2C2 element is found by 6(0)-3(-1)=9
:
highlight((matrix(2,2,-10,8,12,9)))

Question 175531: How do I solve the system of equations using the Gauss-Jordan elimination?
3x+5y=7
6x-y=-8
: How do I solve the system of equations using the Gauss-Jordan elimination?
3x+5y=7
6x-y=-8

Answer by Mathtut(1329) About Me  (Show Source):
You can put this solution on YOUR website!

start with augmented matrix
:
(matrix(2,3,3,5,7,6,-1,-8))(R1)/3(matrix(2,3,1,5/3,7/3,6,-1,-8))-6R1+R2(matrix(2,3,1,5/3,7/3,0,-11,-22))R2/-11(matrix(2,3,1,5/3,7/3,0,1,2))-(5/3)R2+R1highlight((matrix(2,3,1,0,-1,0,1,2)))
:
answer is system(x=-1,y=2)


remember that R1 is Row 1
.................R2 is Row 2
:
and when you see something like R1/3 that is all the elements in Row 1 being divided by 3. Maybe you'll see 6R1+R2..thats elements in Row 1 multiplied by 6 and added to elements in Row 2.
Question 175531: How do I solve the system of equations using the Gauss-Jordan elimination?
3x+5y=7
6x-y=-8
: How do I solve the system of equations using the Gauss-Jordan elimination?
3x+5y=7
6x-y=-8

Answer by stanbon(19714) About Me  (Show Source):
You can put this solution on YOUR website!
solve the system of equations using the Gauss-Jordan elimination?
3x+5y=7
6x-y=-8
-------------
Multiply thru the 2nd equation by 5 to get:
30x - 5y = -40
Add that to the 1st equation to solve for "x":
33x = -33
x = -1
-------------
Substitute into 3x+5y=7 to solve for "y":
3*-1 + 5y = 7
5y = 10
y = 2
==================
Cheers,
Stan H.

Question 175530: How do I find the determinant of K?
K= 14 -13 0
3 8 -1
-10 -2 5
: How do I find the determinant of K?
K= 14 -13 0
3 8 -1
-10 -2 5

Answer by jim_thompson5910(9911) About Me  (Show Source):
You can put this solution on YOUR website!
Solved by pluggable solver: Finding the Determinant of a 3x3 Matrix

If you have the general 3x3 matrix:

(matrix(3,3,a,b,c,d,e,f,g,h,i))

the determinant is: abs(matrix(3,3,a,b,c,d,e,f,g,h,i))=a*abs(matrix(2,2,e,f,h,i))-b*abs(matrix(2,2,d,f,g,i))+c*abs(matrix(2,2,d,e,g,h))

Which further breaks down to:

abs(matrix(3,3,a,b,c,d,e,f,g,h,i))=a(ei-fh)-b*(di-fg)+c(dh-eg)

Note: abs(matrix(2,2,e,f,h,i)), abs(matrix(2,2,d,f,g,i)) and abs(matrix(2,2,d,e,g,h)) are determinants themselves.
If you need help finding the determinant of 2x2 matrices (which is required to find the determinant of 3x3 matrices), check out this solver

--------------------------------------------------------------


From the matrix (matrix(3,3,14,-13,0,3,8,-1,-10,-2,5)), we can see that a=14, b=-13, c=0, d=3, e=8, f=-1, g=-10, h=-2, and i=5

abs(matrix(3,3,a,b,c,d,e,f,g,h,i))=a(ei-fh)-b*(di-fg)+c(dh-eg) Start with the general 3x3 determinant.

abs(matrix(3,3,14,-13,0,3,8,-1,-10,-2,5))=(14)((8)(5)-(-1)(-2))-(-13)((3)(5)-(-1)(-10))+(0)((3)(-2)-(8)(-10)) Plug in the given values (see above)

abs(matrix(3,3,14,-13,0,3,8,-1,-10,-2,5))=(14)(40-2)-(-13)(15-10)+(0)(-6--80) Multiply

abs(matrix(3,3,14,-13,0,3,8,-1,-10,-2,5))=(14)(38)-(-13)(5)+(0)(74) Subtract

abs(matrix(3,3,14,-13,0,3,8,-1,-10,-2,5))=532--65+0 Multiply

abs(matrix(3,3,14,-13,0,3,8,-1,-10,-2,5))=597 Combine like terms.


======================================================================


Answer:

So abs(matrix(3,3,14,-13,0,3,8,-1,-10,-2,5))=597, which means that the determinant of the matrix (matrix(3,3,14,-13,0,3,8,-1,-10,-2,5)) is 597

Question 175528: How do I find the determinant of A?
A= 4 -7
3 -2
: How do I find the determinant of A?
A= 4 -7
3 -2

Answer by actuary(81) About Me  (Show Source):
You can put this solution on YOUR website!
Determinant of A = 4*(-2)-3*(-7)=-8+21=13
I hope that this helps

Question 175529: What is the determinant of G?
G= 12 0
-6 2
: What is the determinant of G?
G= 12 0
-6 2

Answer by actuary(81) About Me  (Show Source):
You can put this solution on YOUR website!
Determinant of G = 12(2)-0*(-6)=24-0=24
I hope that this helps
Question 175529: What is the determinant of G?
G= 12 0
-6 2
: What is the determinant of G?
G= 12 0
-6 2

Answer by Mathtut(1329) About Me  (Show Source):
You can put this solution on YOUR website!
detG=det(matrix(2,2,12,0,-6,2))= 12(2)-0(-6)=24

Question 175429: How do I find the element of a(base 1),(base 2)?
1 2 3
4 5 6
7 8 9
: How do I find the element of a(base 1),(base 2)?
1 2 3
4 5 6
7 8 9

Answer by Edwin McCravy(2190) About Me  (Show Source):
You can put this solution on YOUR website!
How do I find the element of a(base 1),(base 2)?

You shouldn't put the word "base" there. You should put "row 1" 
instead of "base 1" and "column 2" instead of "base 2". The 
first number in a[r,c], the r, is the row number 
going from top to bottom, and the second number c is the 
column number going from left to right.  You can remember which
is which by remembring that a[r,c] looks like the word 
"arc".  

          C C C 
          O O O 
          L L L
          U U U
          M M M
          N N N
          # # # 
          1 2 3 
             
ROW #1  1 2 3 
ROW #2  4 5 6 
ROW #3  7 8 9

The 1 is in ROW #1 and COLUMN #1, so 1 is the element a[1,1]
The 2 is in ROW #1 and COLUMN #2, so 2 is the element a[1,2]
The 3 is in ROW #1 and COLUMN #3, so 3 is the element a[1,3]
The 4 is in ROW #2 and COLUMN #1, so 4 is the element a[2,1]
The 5 is in ROW #2 and COLUMN #2, so 5 is the element a[2,2]
The 6 is in ROW #2 and COLUMN #3, so 6 is the element a[2,3]
The 7 is in ROW #3 and COLUMN #1, so 7 is the element a[3,1]
The 8 is in ROW #3 and COLUMN #2, so 8 is the element a[3,2]
The 9 is in ROW #3 and COLUMN #3, so 9 is the element a[3,3]

Your answer is the red one.

Edwin

Question 175430: How do I find matrix A + matrix B?
A= [3,0,2,-1] B=[2,8,.6,3]
: How do I find matrix A + matrix B?
A= [3,0,2,-1] B=[2,8,.6,3]

Answer by actuary(81) About Me  (Show Source):
You can put this solution on YOUR website!
Matrix addition and subtraction is performed by adding/subtracting comparable components of each matrix.
A+B = [3+2,0+8,2+.6,-1+3]=[5,8,2.6,2]
I hope that this helps

Question 175434: How do I complete the multiplication: 2EA
E= [1,2] A=[3,0,2,-1]
: How do I complete the multiplication: 2EA
E= [1,2] A=[3,0,2,-1]

Answer by Mathtut(1329) About Me  (Show Source):
You can put this solution on YOUR website!
I am assuming that A is a 2x2 since you cannot multiply a 1x2 and a 1x4 matrix
:
(matrix(1,2,1,2))(matrix(2,2,3,0,2,-1))=(matrix(1,2,-1,2))
:
now multiply by 2 (matrix(1,2,-1,2))=(matrix(1,2,-2,4))

Question 175433: How do I find 4c?
C= [12,0,3over2, 1,-6,7]
: How do I find 4c?
C= [12,0,3over2, 1,-6,7]

Answer by Mathtut(1329) About Me  (Show Source):
You can put this solution on YOUR website!
4c=4(12)=48
4c=4(0)=0
4c=4(3/2)=6
4c=4(1)=4
4c=4(-6)=-24
4c=4(7)=28
:
(matrix(1,6,48,0,6,4,-24,28))
Question 175433: How do I find 4c?
C= [12,0,3over2, 1,-6,7]
: How do I find 4c?
C= [12,0,3over2, 1,-6,7]

Answer by EMStelley(36) About Me  (Show Source):
You can put this solution on YOUR website!
4C is just the matrix that has all the same elements as C, only multiplied by 4. For example, the first element would be 4(12) = 48.

Question 175330: Cramers rule Cant find this problem here
Solve the system of equation using Cramer's Rule if it is applicable. If Cramer's Rule is not applicable, say so.
Parenthesis 2x+3y=41
2x-3y=-13
A Parenthesis is only in the beginning then the two equations top and bottom..
here are the choices I need
A. x=7,y=9 B. x=-9,y=7 C. x=-7,y=-9 D. x=9,y=7
I think it is B is that correct?
Help
: Cramers rule Cant find this problem here
Solve the system of equation using Cramer's Rule if it is applicable. If Cramer's Rule is not applicable, say so.
Parenthesis 2x+3y=41
2x-3y=-13
A Parenthesis is only in the beginning then the two equations top and bottom..
here are the choices I need
A. x=7,y=9 B. x=-9,y=7 C. x=-7,y=-9 D. x=9,y=7
I think it is B is that correct?
Help

Answer by nycsub_teacher(90) About Me  (Show Source):
You can put this solution on YOUR website!
Determinants can be used to solve a linear system of equations using Cramer’s Rule.
Cramer’s Rule is used for Two Equations in Two Variables, which is what you have: variables x and y.
2x+3y = 41
2x-3y = -13
To find the determinant, we use:
D = 2(-3) - 2(3)
D = -6 -6
D = -12
To find x use:
x = Dx/D
We already know D, right?
We need to find Dx.
We find Dx = 41(-3) - 3(-13)
Dx = -123 + 39
Dx = -84
We can now find x.
So, x = -84/-12
Then x = 7
Lastly, we need to find y.
y = Dy/D
We know D to be -12, right?
To find y, we need to first find Dy.
We can find Dy = 2(-13) - 2(41)
Dy = -26 - 82
Dy = -108
We can now find y.
y = -108/-12
y = 9
The solution to the above system of equations in two variables is the point
(7, 9)
The two equations given to you meet or cross each other at the point (7, 9) and so, this is why that particular point is the solution.
Understood?
The answer is choice (A).



Question 175330: Cramers rule Cant find this problem here
Solve the system of equation using Cramer's Rule if it is applicable. If Cramer's Rule is not applicable, say so.
Parenthesis 2x+3y=41
2x-3y=-13
A Parenthesis is only in the beginning then the two equations top and bottom..
here are the choices I need
A. x=7,y=9 B. x=-9,y=7 C. x=-7,y=-9 D. x=9,y=7
I think it is B is that correct?
Help
: Cramers rule Cant find this problem here
Solve the system of equation using Cramer's Rule if it is applicable. If Cramer's Rule is not applicable, say so.
Parenthesis 2x+3y=41
2x-3y=-13
A Parenthesis is only in the beginning then the two equations top and bottom..
here are the choices I need
A. x=7,y=9 B. x=-9,y=7 C. x=-7,y=-9 D. x=9,y=7
I think it is B is that correct?
Help

Answer by KnightOwlTutor(291) About Me  (Show Source):
You can put this solution on YOUR website!
If you plug in the x and y values for b you will find it incorrect.
x=-9,y=7
2x+3y=41 -18+21=39
2x-3y=-13 -18-21=-39
2x+3y=41
2x-3y=-13
Add each column
4x+0=28
divide both sides by 4
x=7
Plug in the value of 7 for x to get the y value
14+3y=41
Subtract 14 from both sides
3y=27
divide both sides by 3
y=9
Plug in the values of x and y in the second equation
(2*7)-(3*9)=-13
-13=-13

Question 175157: how do you name a matrix?: how do you name a matrix?
Answer by Mathtut(1329) About Me  (Show Source):
You can put this solution on YOUR website!
can you be more specific...you can name a matrix anything you choose matrix A,
matrix B, matrix (Keanu Reeves)......or anything else you can think of. Naming a matrix or variable within math, is simply a process of identifying that item so that it doesnt get confused with something else.

Question 175039: find inverse of the matrix and also verify your result.
1 -2
3 4
: find inverse of the matrix and also verify your result.
1 -2
3 4

Answer by Mathtut(1329) About Me  (Show Source):
You can put this solution on YOUR website!

A=(matrix(2,2,1,-2,3,4))
A^-1=adjA/detA
:
adjA=(matrix(2,2,4,2,-3,1)) in a 2x2 matrix...the elements of the main diagonal of the matrix A are switched whereas we take the negatives of the remaining elements to obtain the adjugate of A
:
detA=1(4)-2(-3)=10
:
A^-1=(matrix(2,2,4,2,-3,1))/10=(matrix(2,2,2/5,1/5,-3/10,1/10))
:
(matrix(2,2,1,-2,3,4))(matrix(2,2,2/5,1/5,-3/10,1/10))=(matrix(2,2,1,0,0,1))

Question 174937: Please help me solve this equations: a+2c+3e+2f=270: Please help me solve this equations: a+2c+3e+2f=270
Answer by Alan3354(1926) About Me  (Show Source):
You can put this solution on YOUR website!
Solve for what?

Question 174936: Please help me solve this equations: a+2c+3e+2f=270: Please help me solve this equations: a+2c+3e+2f=270
Answer by checkley75(3416) About Me  (Show Source):
You can put this solution on YOUR website!
a+2c+3e+2f=270
There is no UNIQUE solution to this equation because you have 4 unknowns & only one equation.
However you can make up a table & find many combinations od a, c, e & f that satisfus this equation thus:
a---2c---3e---2f=270
50+2*25+3*10+2*70=270
50+50+30+140=270
OR
100+2*10+3*20+2*45=270
100+20+60+90=270
270=270
And there are many additional combinations of a,c,e & f that are solutions.

Question 174917: i have the following 3x3 matrix
1,2,-1
2,1,4 = A
1,-2,1
i need to evaluate A^2 and A^3 but i cant even figure out where to start, any help would be greatly appreciated
: i have the following 3x3 matrix
1,2,-1
2,1,4 = A
1,-2,1
i need to evaluate A^2 and A^3 but i cant even figure out where to start, any help would be greatly appreciated

Answer by actuary(81) About Me  (Show Source):
You can put this solution on YOUR website!
The problem asks you to multiply matrices. A^2 =A*A and A^3=A*A*A

1,2,-1
A = 2,1,4
1,-2,1
The first row, first column of A*A = A^2 is calculated by multiplying each element of the first row of A by each element of the first column of A and then each of the products are added together.
The second row, first column of A*A = A^2 is calculated by each element of the second row of A by each element of the first column of A and then each of the products are added together.
The third row, first column element of A*A = A^2 is calculated by each element of the third row of A by each element of the first column of A and then each of the products are added together.
The general rule that is being used is the i'th row and j'th column element of the result is found by multiplying each element in the i'th row of one matrix(multiplier) by each element of the j'th column of the other matrix (multiplican) and then the products are added to together.
So to calculate A^2 you have to calculate 9 numbers using the rule that is described above.
Since A^3 = (A^2)*A, you have to calculate 9 numbers using the rule described above with A^2 being one matrix and A the other matrix.
I hope that this helps but it does take some practice to understand and be able to do matrix multiplication.
Good luck.



Question 174862: I have to determine the number of each type of seats in a 2400 seat stadium and solve the equation: n= number of nosebleed seats; g=number of general admission seats and p= number of press box seats.: I have to determine the number of each type of seats in a 2400 seat stadium and solve the equation: n= number of nosebleed seats; g=number of general admission seats and p= number of press box seats.
Answer by Mathtut(1329) About Me  (Show Source):
You can put this solution on YOUR website!
we need the rest of the information for this problem

Question 174705: [6-a 4] * [-2] = [2a]
[-3 -3(d-2] * [3] = [-3]

find a and d... this is a matrice
: [6-a 4] * [-2] = [2a]
[-3 -3(d-2] * [3] = [-3]

find a and d... this is a matrice

Answer by stanbon(19714) About Me  (Show Source):
You can put this solution on YOUR website!
[6-a 4] * [-2] = [2a]
[-3 -3(d-2] * [3] = [-3]
----------------------------------------
(6-a)(-2) + 4*3 = 2a
-12+2a + 12 = 2a
2a = 2a
a is indeterminate
-------------------------
-3*-2 + -2(d-2)(3) = -3
6 - 6(d-2) = -3
-6d+12 = -9
-6d = -21
d = 7/2
-------------------------
Cheers,
Stan H.

Question 174673This question is from textbook Prentic Hall Mathematics Algebra 2
: In this problem, they give me the diagram of a rectangle with a diagonal dividing it in two triangles. Each corner is labeled with A, B, C, and D.
The perimeter of a rectangle is 28 cm. The perimeter of each of the triangles is 24 cm. The diagonal of the rectangle is 2 cm longer than the longer side of the rectangle.
How do you write a system of three questions in three unknowns?
How do you simplify the system to a system of two equations in two unknowns?
And how can I write an augmented matrix for the system?
This is what I've done so far:
2a+2b=28
a+b+x=24
2+a=?
Thankyou&Happy New Year!!
This question is from textbook Prentic Hall Mathematics Algebra 2
: In this problem, they give me the diagram of a rectangle with a diagonal dividing it in two triangles. Each corner is labeled with A, B, C, and D.
The perimeter of a rectangle is 28 cm. The perimeter of each of the triangles is 24 cm. The diagonal of the rectangle is 2 cm longer than the longer side of the rectangle.
How do you write a system of three questions in three unknowns?
How do you simplify the system to a system of two equations in two unknowns?
And how can I write an augmented matrix for the system?
This is what I've done so far:
2a+2b=28
a+b+x=24
2+a=?
Thankyou&Happy New Year!!

Answer by stanbon(19714) About Me  (Show Source):
You can put this solution on YOUR website!
The perimeter of a rectangle is 28 cm. The perimeter of each of the triangles is 24 cm. The diagonal of the rectangle is 2 cm longer than the longer side of the rectangle.
Let shorter side be a; let longer side be b: let diagonal be c
Equations:
2a + 2b = 28
a + b + c = 24
c = b + 2
write a system of three questions in three unknowns
---------------
Rearrange the equations:
2a + 2b + 0 = 28
a + b + c = 24
0 + b - c = -2
-----------------------------
simplify to a system of two equations in two unknowns?
let b = c+2
Then you get:
2a + 2(c+2) + 0 = 28
a + c+2 + c = 24
----
Rearrange:
2a + 2c = 24
a + 2c = -2
----
write an augmented matrix for the system?

2...2..|..24
1...2..|..-2
=====================
Cheers,
Stan H.
Question 174673This question is from textbook Prentic Hall Mathematics Algebra 2
: In this problem, they give me the diagram of a rectangle with a diagonal dividing it in two triangles. Each corner is labeled with A, B, C, and D.
The perimeter of a rectangle is 28 cm. The perimeter of each of the triangles is 24 cm. The diagonal of the rectangle is 2 cm longer than the longer side of the rectangle.
How do you write a system of three questions in three unknowns?
How do you simplify the system to a system of two equations in two unknowns?
And how can I write an augmented matrix for the system?
This is what I've done so far:
2a+2b=28
a+b+x=24
2+a=?
Thankyou&Happy New Year!!
This question is from textbook Prentic Hall Mathematics Algebra 2
: In this problem, they give me the diagram of a rectangle with a diagonal dividing it in two triangles. Each corner is labeled with A, B, C, and D.
The perimeter of a rectangle is 28 cm. The perimeter of each of the triangles is 24 cm. The diagonal of the rectangle is 2 cm longer than the longer side of the rectangle.
How do you write a system of three questions in three unknowns?
How do you simplify the system to a system of two equations in two unknowns?
And how can I write an augmented matrix for the system?
This is what I've done so far:
2a+2b=28
a+b+x=24
2+a=?
Thankyou&Happy New Year!!

Answer by Mathtut(1329) About Me  (Show Source):
You can put this solution on YOUR website!
let L and W be the sides of the rectangle and Z be the diagonal
:
2L+2W=28.....eq 1
L+W+Z=24.....eq 2
L+2=Z........eq 3
:
take Z's value of L+2 from eq 3 and plug it into eq 2
:
L+W+(L+2)=24--->2L+W=22....revised eq 2
:
now we have 2 eq with 2 unknownssystem(2L+2W=28,2L+ W=22)
:
augmented matrix(matrix(2,3,2,2,28,2,1,22))

Question 174668This question is from textbook Algebra 2, Texas Edition
: As a participant in your school's community service project, you volunteer a total of 40 hours over the course of the school year. Your volunteer hours include serving at a soup kitchen, picking up trash at several local parks, and collecting toys for needy children. You spend 4 times as many hours collecting toys as picking up trash, and 2 hours less serving at the soup kitchen than picking up trash. Slove this system of equations using Cramer's Rule. Suppose you cannot remember the total number of hours you volunteered. From the remaining information, can you still determine how many hours you spend doing each volunteer activity? Why or why not?This question is from textbook Algebra 2, Texas Edition
: As a participant in your school's community service project, you volunteer a total of 40 hours over the course of the school year. Your volunteer hours include serving at a soup kitchen, picking up trash at several local parks, and collecting toys for needy children. You spend 4 times as many hours collecting toys as picking up trash, and 2 hours less serving at the soup kitchen than picking up trash. Slove this system of equations using Cramer's Rule. Suppose you cannot remember the total number of hours you volunteered. From the remaining information, can you still determine how many hours you spend doing each volunteer activity? Why or why not?
Answer by Mathtut(1329) About Me  (Show Source):
You can put this solution on YOUR website!

lets call the time spent at soup kitchen,trash pickup, and toy collecting
s, t, and c, respectively
:
c=4t...........eq 1
s=t-2..........eq 2
s+t+c=40.......eq 3
:
rewrite equations
:
s+t+c=40......eq 3
s-t+0c=-2.....eq 2
0s-4t+c=0......eq 1
:
now writing out the main matrix
:
(matrix(3,3,1,1,1,1,-1,0,0,-4,1))...lets call this matrix X
:
we need to find the determinant of this matrix to begin with
:
we can choose any row or column to determine this ..I will work with column 1 since it has a zero in it
:
det X=(1) det(matrix(2,2,-1,0,-4,1))-(1)det(matrix(2,2,1,1,-4,1))+0=
.....1(-1)-1(5)=-6
:
s=det s/-6 where matrix s is matrix X with the 1st column replaced by constant coefficents 40,-2,0. I will use column one for our determinant
:
det s = 40 det(matrix(2,2,-1,0,-4,1))-(-2)det(matrix(2,2,1,1,-4,1))
=40(-1)+2(5)=-30
:
s=det s/-6=highlight(-30/-6=5)hours in the soup kitchen
:
:
t=det t/-6 where matrix t is matrix X with the 2nd column replaced by constant coefficents 40,-2,0. I will use row 3 for our determinant as it has 2 zeros
:
det t=0+0+(1)det(matrix(2,2,1,40,1,-2))=1(-42)=-42
:
t=det t/-6=highlight(-42/-6=7)hours picking up trash
:
:
c=det c/-6 where matrix c is matrix X with the 3rd column replaced by constant coefficents 40,-2,0. I will use row 3 for our determinant as it has 2 zeros
:
det c= 0-(-4)(matrix(2,2,1,40,1,-2))+0=4(-42)=-168
:
c=det c/-6=highlight(-168/-6=28)hours toy collecting

If you forgot the number of hours you volunteered you could not determine the hours you spend doing each activity....
:
you would only have 2 equations and 3 unknowns


Question 174551This question is from textbook Algebra 2, Texas Edition
: As a participant in your school's community service project, you volunteer a total of 40 hours over the course of the school year. Your volunteer hours include serving at a soup kitchen, picking up trash at several local parks, and collecting toys for needy children. You spend 4 times as many hours collecting toys as picking up trash, and 2 hours less serving at the soup kitchen than picking up trash.
1. Solve this system of equations using Cramer's Rule.
This question is from textbook Algebra 2, Texas Edition
: As a participant in your school's community service project, you volunteer a total of 40 hours over the course of the school year. Your volunteer hours include serving at a soup kitchen, picking up trash at several local parks, and collecting toys for needy children. You spend 4 times as many hours collecting toys as picking up trash, and 2 hours less serving at the soup kitchen than picking up trash.
1. Solve this system of equations using Cramer's Rule.

Answer by Mathtut(1329) About Me  (Show Source):
You can put this solution on YOUR website!
1. Write a system of equations to represent the given information and solve using the substitution method.
Please help and try to show every bit of work that you can to help me better understand the problem, Thank You! =)
:
lets call the time spent at soup kitchen,trash pickup, and toy collecting
s, t, and c, respectively
:
c=4t...........eq 1
s=t-2..........eq 2
s+t+c=40.......eq 3
:
rewrite equations
:
s+t+c=40......eq 3
s-t+0c=-2.....eq 2
0s-4t+c=0......eq 1
:
now writing out the main matrix
:
(matrix(3,3,1,1,1,1,-1,0,0,-4,1))...lets call this matrix X
:
we need to find the determinant of this matrix to begin with
:
we can choose any row or column to determine this ..I will work with column 1 since it has a zero in it
:
det X=(1) det(matrix(2,2,-1,0,-4,1))-(1)det(matrix(2,2,1,1,-4,1))+0=
.....1(-1)-1(5)=-6
:
s=det s/-6 where matrix s is matrix X with the 1st column replaced by constant coefficents 40,-2,0. I will use column one for our determinant
:
det s = 40 det(matrix(2,2,-1,0,-4,1))-(-2)det(matrix(2,2,1,1,-4,1))
=40(-1)+2(5)=-30
:
s=det s/-6=highlight(-30/-6=5)hours in the soup kitchen
:
:
t=det t/-6 where matrix t is matrix X with the 2nd column replaced by constant coefficents 40,-2,0. I will use row 3 for our determinant as it has 2 zeros
:
det t=0+0+(1)det(matrix(2,2,1,40,1,-2))=1(-42)=-42
:
t=det t/-6=highlight(-42/-6=7)hours picking up trash
:
:
c=det c/-6 where matrix c is matrix X with the 3rd column replaced by constant coefficents 40,-2,0. I will use row 3 for our determinant as it has 2 zeros
:
det c= 0-(-4)(matrix(2,2,1,40,1,-2))+0=4(-42)=-168
:
c=det c/-6=highlight(-168/-6=28)hours toy collecting





Question 174531This question is from textbook Algebra 2
: While stranded on an island, the crew of a sailboat has access to only three sources of food, as shown in the table below. One of the crew members designs a daily diet to supply each person with 120g of fat, 220g of carbohydrates, and 80g of protein.
_______________ A______B_______C
Fat____________ 10 g____ 4g_____ 12 g
Carbohydrates___11 g___77 g_____0g
Protein_________4 g_____1 g_____16 g
A. Write a system of three equations in three variables to find the number of portions of each food each person must have to meet the daily diet.
B. Use an augmented matrix to solve the system of equations from part (a).
C. Suppose food C runs out. How would this change the number of portions of food required each day?
This question is from textbook Algebra 2
: While stranded on an island, the crew of a sailboat has access to only three sources of food, as shown in the table below. One of the crew members designs a daily diet to supply each person with 120g of fat, 220g of carbohydrates, and 80g of protein.
_______________ A______B_______C
Fat____________ 10 g____ 4g_____ 12 g
Carbohydrates___11 g___77 g_____0g
Protein_________4 g_____1 g_____16 g
A. Write a system of three equations in three variables to find the number of portions of each food each person must have to meet the daily diet.
B. Use an augmented matrix to solve the system of equations from part (a).
C. Suppose food C runs out. How would this change the number of portions of food required each day?

Answer by Mathtut(1329) About Me  (Show Source):
You can put this solution on YOUR website!
120g of fat, 220g of carbohydrates, and 80g of protein.
_______________ A______B_______C
Fat____________ 10 g____ 4g_____ 12 g
Carbohydrates___11 g___77 g_____0g
Protein_________4 g_____1 g_____16 g
:
:
A)10A+4B+12C=120
11A+77B =220
4A+ 1B+16C=80
:
B)using cramers rule
:
find determinant of main matrix(matrix(3,3,10,4,12,11,77,0,4,1,16))using column 3---> 12(matrix(2,2,11,77,4,1))-0(matrix(2,2,10,4,4,1))+16(matrix(2,2,10,4,11,77))---->12(-297)+16(726)=8052
:
A=det(matrix(3,3,120,4,12,220,77,0,80,1,16))/8052---->so using the 3rd column--->det = 12(matrix(2,2,220,77,80,1))-0+16(matrix(2,2,120,4,220,77))--->12(-5940)+16(8360)=62480
:highlight(A=62480/8052=7.76)
:
:
B=det(matrix(3,3,10,120,12,11,220,0,4,80,16))/8052---->so using the 3rd column--->det = 12(matrix(2,2,11,220,4,80))-0+16(matrix(2,2,10,120,11,220))---->0+16(880)=14080
:highlight(B=14080/8052=1.75)
:
C=det(matrix(3,3,10,4,120,11,77,220,4,1,80))/8052---->using column 1--->det= 10(matrix(2,2,77,220,1,80))-11(matrix(2,2,4,120,1,80))+4(matrix(2,2,4,120,77,220))--->10(5940)-11(200)+4(-8360)--->59400-2200-33440=
23760
:highlight(C=23760/8052=4.37)
:
:
C)if C was no longer available we would have the equation
:
10A+4B+0C=120
11A+77B+0C=220
4A+ B+0C=80
:
we cannot use Cramers rule because there would be no unique solution as the determinant you would be dividing by would be zero.
:according to this graph there is no unique solution to this scenario.
It appears you could reach 2 of the conditions in any order but not all 3 at once.
graph(300,300,-100,50,-100,50,(-5/2)x+30,(-1/7)x+220/77,-4x+80)

Question 174568: What is the solution to:
system(4x + 5y - 6z = -15,<BR>
-6x + 5y - 4z = 35,<BR>
2x + 3y - 3z = -7)
: What is the solution to:
system(4x + 5y - 6z = -15,<BR>
-6x + 5y - 4z = 35,<BR>
2x + 3y - 3z = -7)

Answer by Edwin McCravy(2190) About Me  (Show Source):
You can put this solution on YOUR website!
What is the solution to:
system(4x + 5y - 6z = -15,<BR>
-6x + 5y - 4z = 35,<BR>
2x + 3y - 3z = -7)

The solution to that system is:

matrix(1,7,

   '(x,', 'y,', 'z)',   '=',   '(-5,', '1,', '0)' )

If you want to know how to get that solution,
post again stating which method you are
studying.  There are a number of different
ways of solving it, so please be sure to
state which method.  But, of course, all
ways lead to the same solution.

Edwin

Question 174542This question is from textbook Algebra 2
: Hi. As of now I've been for almost two hours trying to solve the same problem, and I just can't. I don't know if it's correct, or not, the thing is that i have pages after pages of work, and I just don't seem to arrive to reasonable answer. could you please help?
While stranded on an island, the crew of a sailboat has access to only three sources of food, as shown in the table below. One of the crew members designs a daily diet to supply each person with 120g of fat, 220g of carbohydrates, and 80g of proteins.
_______________ A______B_______C
Fat____________ 10 g____ 4g_____ 12 g
Carbohydrates___11 g___77 g_____0g
Protein_________4 g_____1 g_____16 g
A. Write a system of three equations in three variables to find the number of portions of each food each person must have to meet the daily diet.
Ok, so this one I know it has to be:
10a+4b+12c=120
11a+77b+0c=220
4a+1b+16c=80
B. Use an augmented matrix to solve the system of equations from part (a). Round each answer to the nearest tenth.
Here I just got lost. I watched some videos and did everything they did, and somehow i got a=428/27, b=0, and c=-540/17. But then i tried to do everything by solve in the graphing calculator and the answers were completely different
C. Suppose food C runs out. How would this change the number of portions of food required each day?
Please, help.
This question is from textbook Algebra 2
: Hi. As of now I've been for almost two hours trying to solve the same problem, and I just can't. I don't know if it's correct, or not, the thing is that i have pages after pages of work, and I just don't seem to arrive to reasonable answer. could you please help?
While stranded on an island, the crew of a sailboat has access to only three sources of food, as shown in the table below. One of the crew members designs a daily diet to supply each person with 120g of fat, 220g of carbohydrates, and 80g of proteins.
_______________ A______B_______C
Fat____________ 10 g____ 4g_____ 12 g
Carbohydrates___11 g___77 g_____0g
Protein_________4 g_____1 g_____16 g
A. Write a system of three equations in three variables to find the number of portions of each food each person must have to meet the daily diet.
Ok, so this one I know it has to be:
10a+4b+12c=120
11a+77b+0c=220
4a+1b+16c=80
B. Use an augmented matrix to solve the system of equations from part (a). Round each answer to the nearest tenth.
Here I just got lost. I watched some videos and did everything they did, and somehow i got a=428/27, b=0, and c=-540/17. But then i tried to do everything by solve in the graphing calculator and the answers were completely different
C. Suppose food C runs out. How would this change the number of portions of food required each day?
Please, help.

Answer by rapaljer(2819) About Me  (Show Source):
You can put this solution on YOUR website!
I have a feeling no one is helping you on this because we are all stumped by it too!! I'm retired, and particularly bored today, so I thought I would give it a looksee! I would say first of all, for you to go with your calculator solution!!

I haven't worked with matrices for a VERY long time, but, if your equations are correct and I think they are correct, you need to convert from this system of equations to one in which you have eliminated coefficients to leave 0s and 1s. You may have to try a few times and I must admit that I didn't get the calculator answers the first time. This is what I did. First, reduce the equations to smaller numbers:
10a + 4b + 12c = 120 (Divide by 2)
11a + 77b + 0c = 220 (Divide by 11)
4a + 1b + 16c = 80

5a + 2b + 6c = 60
a + 7b + 0c = 20 (Mult by -4 and add to eq #3)
4a + 1b + 16c = 80

5a + 2b + 6c = 60
a + 7b + 0c = 20 (Mult by -5 and add to eq #1)
0a - 27b + 16c = 0

5a + 2b + 6c = 60
0a - 33b + 6c = -40
0a - 27b + 16c = 0

Next, eliminate the b coefficients by multiplying Eq #2 times -27 and Eq #3 times 33 and add together. (The first two equations remain the same!)
5a + 2b + 6c = 60
0a - 33b + 6c = -40
0a + 0b + 366c = 1080


Next, divide the Eq #3 by 366:
5a + 2b + 6c = 60
0a - 33b + 6c = -40
0a + 0b + 1c = 1080/366

So, c= 1080/366 = 2.9508 approximately, which is the calculator value that I got. I'm sure you can finish this now. By the way, my other calculator values were a=7.759 and b= 1.7486 approximately.

Good luck!!

R^2




Question 174529This question is from textbook Algebra 2
: Hi. I have tried solving this, but I am not sure if it's right and would really appreciate your help.
A hardware store mixes paints in a ratio of two parts red to six parts yellow to make pumpkin orange. A ratio of five parts red to three parts yellow makes red-pepper red. A gallon of pumpkin orange sells for $25, and a gallon of red-pepper red sells for $28.
A. Write a system of equations to model the situation (for this one i wrote
2r+6y=25 and 5r+3y=28, but I dont know if it is correct)
B. Solve the system (I got r=31/8 and y=23/8)
C. Find the cost of 1qt of red paint and the cost of 1qt of yellow paint. Ok, this one I don't know.
I would really appreciate your help. THANKS!
This question is from textbook Algebra 2
: Hi. I have tried solving this, but I am not sure if it's right and would really appreciate your help.
A hardware store mixes paints in a ratio of two parts red to six parts yellow to make pumpkin orange. A ratio of five parts red to three parts yellow makes red-pepper red. A gallon of pumpkin orange sells for $25, and a gallon of red-pepper red sells for $28.
A. Write a system of equations to model the situation (for this one i wrote
2r+6y=25 and 5r+3y=28, but I dont know if it is correct)
B. Solve the system (I got r=31/8 and y=23/8)
C. Find the cost of 1qt of red paint and the cost of 1qt of yellow paint. Ok, this one I don't know.
I would really appreciate your help. THANKS!

Answer by josmiceli(2170) About Me  (Show Source):
You can put this solution on YOUR website!
Let r = the cost per gallon of red paint
Let y = the cost per gallon of yellow paint
Given is:
A hardware store mixes paints in a ratio of two parts red to six parts yellow to make pumpkin orange.
Therefore, The gallons of red per gallon of punpkin orange is
2/(2 + 6)gal
1/4gal
The gallons of yellow per gallon of pumpkin orange is
6/(2 + 6)gal
3/4gal
Therefore,
(1) (1/4)r + (3/4)y = 25
Also given:
A ratio of five parts red to three parts yellow makes red-pepper red.
The gallons of red in a gallon of red-pepper red is
5/(3 + 5)gal
5/8gal
The gallons of yellow in a gallon of red-pepper red is
3/8gal
Therefore,
(2) (5/8)r + (3/8)y = 28
(A)
Multiply both sides of (1) by 4
(1) r + 3y = 100
Multiply both sides of (2) by 8
(2) 5r + 3y = 224
(B)
Subtract (1) from (2)
4r = 124
r = 31
Substitute this in (1)
31 + 3y = 100
3y = 69
y = 23
The cost per gallon of red paint is $31
The cost per gallon of yellow paint is $23
(C) There are 4 quarts in a gallon,so
red paint is
31/4 = 7.75/qt
yellow paint is
23/4 = 5.75/qt

Question 174521This question is from textbook Algebra 2
: Hi. I'm having a lot of trouble with this question. Suppose you invested $5000 in three different funds for one year. The funds paid simple interest of 8%, 10%, and 7%, respectively. The total interest at the end of one year was $405. You invested $500 more at 10% than at 8%. How much did you invest in the 10% fund?
The answer of the book is $1500, but I really need to know how to get there and I would really appreciate it your help. THANKS!
This question is from textbook Algebra 2
: Hi. I'm having a lot of trouble with this question. Suppose you invested $5000 in three different funds for one year. The funds paid simple interest of 8%, 10%, and 7%, respectively. The total interest at the end of one year was $405. You invested $500 more at 10% than at 8%. How much did you invest in the 10% fund?
The answer of the book is $1500, but I really need to know how to get there and I would really appreciate it your help. THANKS!

Answer by Earlsdon(3816) About Me  (Show Source):
You can put this solution on YOUR website!
Let x = the amount invested at 10%, then x-500 = the amount invested at 8%, so that 2x-500 would be the amount invested at 7%.
The sum of the three invested amounts (x)+(x-500)+(2x-500) is $5,000.
Now let's look at the amounts of interest earned on these amounts:
x(0.1) is the amount earned at 10 %.
(x-500)(0.08) is the amount earned at 8%.
2x-500)(0.07) is the amount earned at 7%.
The sum of these three amounts is given as $405.
So we can write the following equation in x.
0.1x+0.08(x-500)+ 0.07(2x-500) = 405 Simplify and solve for x.
0.1x+0.08x-40+0.14x-35 = 405
0.32x-75 = 405 Add 75 to both sides.
0.32x = 480 Divide both sides by 0.32
highlight(x = 1500)
$1,500 was invested at 10%
Check:
x+(x-500)+(2x-500) = 5000
1500+(1500-500)+(3000-500) = 5000
1500+1000+2500 = 5000
5000 = 5000

Question 174415:

what is the value of this determinant?
abs(matrix(6,6,
1,   1,   1,   1,   1,   1,
0,   1,   0,  -1,   0,  -1,
1,   2,   0,   3,   2,   0,
1,   0,   3,   2,   0,   2,
1,   2,   0,   4,   1,   5,
1,   0,   0,   2,   3,   4))
                             thank you!
:

what is the value of this determinant?
abs(matrix(6,6,
1,   1,   1,   1,   1,   1,
0,   1,   0,  -1,   0,  -1,
1,   2,   0,   3,   2,   0,
1,   0,   3,   2,   0,   2,
1,   2,   0,   4,   1,   5,
1,   0,   0,   2,   3,   4))
                             thank you!

Answer by Edwin McCravy(2190) About Me  (Show Source):
You can put this solution on YOUR website!

what is the value of this determinant?
abs(matrix(6,6,
1,   1,   1,   1,   1,   1,
0,   1,   0,  -1,   0,  -1,
1,   2,   0,   3,   2,   0,
1,   0,   3,   2,   0,   2,
1,   2,   0,   4,   1,   5,
1,   0,   0,   2,   3,   4))
                             thank you!

The third column has the most 0's, so
we'll expand about it after we make it
have all 0's but one.

Let's make the 3 in the 3rd column a 0
by adding -3 times the 1st row to 1
times the 4th row:

matrix(6,1,-3,'','',1,'','')abs(matrix(6,6,
1,   1,   1,   1,   1,   1,
0,   1,   0,  -1,   0,  -1,
1,   2,   0,   3,   2,   0,
1,   0,   3,   2,   0,   2,
1,   2,   0,   4,   1,   5,
1,   0,   0,   2,   3,   4))

abs(matrix(6,6,
1,   1,   1,   1,   1,   1,
0,   1,   0,  -1,   0,  -1,
1,   2,   0,   3,   2,   0,
-2, -3,   0,  -1,  -3,  -1,
1,   2,   0,   4,   1,   5,
1,   0,   0,   2,   3,   4))

Now we expand this 6x6 matrix by
the 3rd column.  Since there is only
1 non-zero element in the 3rd column,
the 1 at the top.  We notice that it
is in row 1 and column 3, so we add
1+3 and get 4, and (-1)^4=+1 we
multiply the 1 in the top row by +1
and so the determinant is +1 times the
5x5 determinant formed by removing
both row 1 and column 3:

abs(matrix(5,5,

0,   1,     -1,   0,  -1,
1,   2,      3,   2,   0,
-2, -3,     -1,  -3,  -1,
1,   2,      4,   1,   5,
1,   0,      2,   3,   4))

The first row has the most 0's, so
we'll expand about it after we make it
have all 0's but one.

Let's make the -1 in the 1st row 3rd 
column a 0 by adding 1 times the 2nd 
column to 1 times the 3rd column:

     1   1
abs(matrix(5,5,
0,   1,     -1,   0,  -1,
1,   2,      3,   2,   0,
-2, -3,     -1,  -3,  -1,
1,   2,      4,   1,   5,
1,   0,      2,   3,   4))

abs(matrix(5,5,
0,   1,      0,   0,  -1,
1,   2,      5,   2,   0,
-2, -3,     -4,  -3,  -1,
1,   2,      6,   1,   5,
1,   0,      2,   3,   4))

Let's make the -1 in the 1st row 5th 
column a 0 by adding 1 times the 2nd 
column to 1 times the 5th column:

     1          1 
abs(matrix(5,5,
0,   1,      0,   0,  -1,
1,   2,      5,   2,   0,
-2, -3,     -4,  -3,  -1,
1,   2,      6,   1,   5,
1,   0,      2,   3,   4))

abs(matrix(5,5,
0,   1,      0,   0,   0,
1,   2,      5,   2,   2,
-2, -3,     -4,  -3,  -4,
1,   2,      6,   1,   7,
1,   0,      2,   3,   4))

Now we expand this 5x5 matrix by
the 1st row.  Since there is only
1 non-zero element in the 1st row,
the 1 at the 1st row 2nd column.
Since it is in row 1 and column 2, so we add
1+2 and get 3, and (-1)^3=-1 we
multiply the 1 in the top row by -1
and so the determinant is -1 times the
4x4 determinant formed by removing
both row 1 and column 2:

-1abs(matrix(4,4,
1,    5,   2,   2,
-2,  -4,  -3,  -4,
1,    6,   1,   7,
1,    2,   3,   4))

We can simplify by multiplying the -1
by the 2nd row, changing their signs
to positive:

abs(matrix(4,4,
1,    5,   2,   2,
2,    4,   3,   4,
1,    6,   1,   7,
1,    2,   3,   4))

Unfortunately there are no 0's at
all.  So we'll make some.  The
simplest row or column is the 1st
column.  To make the 2 in the
1st column a 0, add -2 times the
1st row to 1 times the 2nd row:
matrix(4,1,-2,1,'','')abs(matrix(4,4,
1,    5,   2,   2,
2,    4,   3,   4,
1,    6,   1,   7,
1,    2,   3,   4))

abs(matrix(4,4,
1,    5,   2,   2,
0,   -6,  -1,   0,
1,    6,   1,   7,
1,    2,   3,   4))

Now since that 0 popped up
over there in the second row,
that makes us change plans, for
now we have 2 0's in the 2nd row.

So we change plans and now we 
want to expand about the 2nd
row.  So we can get a 0 where
the -6 is by multiplying the
3rd column by -6 and adding it
to 1 times column 2.

abs(matrix(4,4,
1,   -7,   2,   2,
0,    0,  -1,   0,
1,    0,   1,   7,
1,  -16,   3,   4))

Now we expand this 4x4 matrix by
the 2nd row.  Since there is only
1 non-zero element in the 1st row,
the -1 at the 2nd row 3rd column.
Since it is in row 2 and column 3, we add
2+3 and get 5, and (-1)^5=-1, we
multiply the -1 in the 2nd row 3rd column
by -1 and so the determinant is 1 times the
3x3 determinant formed by removing
both row 2 and column 3:

abs(matrix(3,3,
1,   -7,   2,
1,    0,   7,
1,  -16,   4))

The
simplest row or column is the 2nd
row.  To make the 7 a 0, we add
-7 times the 1st column to 1 times 
the 3rd column:

-7   1
abs(matrix(3,3,
1,   -7,   2,
1,    0,   7,
1,  -16,   4))

abs(matrix(3,3,
1,   -7,  -5,
1,    0,   0,
1,  -16,  -3))

Now we expand this 3x3 matrix by
the 2nd row.  Since there is only
1 non-zero element in the 2nd row,
the 1 at the 2nd row 1st column.
Since it is in row 2 and column 1, we add
2+1 and get 3, and (-1)^3=-1, we
multiply the 1 in the 2nd row 1st column
by -1 and so the determinant is -1 times the
2x2 determinant formed by removing
both row 2 and column 1:

-1abs(matrix(2,2,
   -7,  -5,
  -16,  -3))

We can simplify by multiplying the -1
by the 1st row, which changing the signs:

abs(matrix(2,2,
   7,  5,
  -16,  -3))


To expand, it's just the difference of
the product of the upper left to lower
right diagonal and the product of the
upper right to lower left diagonal.

(7)(-3)-(5)(-16)=-21+80=59

So the value of the determinant is 59.

Edwin


Question 174120: Find the inverse of each matrix, if it exists.

1.[ -2 -1]
[10 7]

2.[-4 2]
[-5 1]
3.[9 -3]
[-6 2]

4. [3 4]
[2 3] x=[6/5]

5. [2 -3] x+[-1 7] [9 12]
[1 2] [-2 4]=[3 10]

6.. [1 -6 0]
[0 1 -7] x=[1]
[3 0 2] [4]
[11]
: Find the inverse of each matrix, if it exists.

1.[ -2 -1]
[10 7]

2.[-4 2]
[-5 1]
3.[9 -3]
[-6 2]

4. [3 4]
[2 3] x=[6/5]

5. [2 -3] x+[-1 7] [9 12]
[1 2] [-2 4]=[3 10]

6.. [1 -6 0]
[0 1 -7] x=[1]
[3 0 2] [4]
[11]

Answer by Mathtut(1329) About Me  (Show Source):
You can put this solution on YOUR website!
 
(matrix(2,2,-2,-1,10,7))
:
take terms a[11]and a[22] and switch their positions. This is simply switching the elements on the main diagonal

take terms a[12]and a[21] and change those numbers to their opposites keeping there positions.
(matrix(2,2,7,1,-10,-2))
:now we find the determinant of this matrix
:
product of the main diagonal-product of the other diagonal
:
-14-(-10)=-4
:
we take that result and divide every element in the matrix and the result is our inverse matrix
:
(matrix(2,2,-7/4,-1/4,5/2,1/2))
the way you can check is to multiply the two together and see if your result is the identity matrix....if it is you can rest easy you have the correct answer.
:
:
:
:
2)and 3)
:
now I will let you do the steps to 2 and 3
:
answers to 2 is (matrix(2,2,1/6,-1/3,5/6,-2/3))
...........3 is no solution as the determinant = 0
:
4)(matrix(2,2,3,4,2,3))X or(matrix(2,1,a,b))=(matrix(2,1,6,5)))
3a+4b=6
2a+3b=5
:
(matrix(2,3,3,4,6,2,3,5))3R2-2R1(Row 2)---->(matrix(2,3,3,4,6,0,1,3))R1-4R2(row 1)---->(matrix(2,3,3,0,-6,0,1,3))1/3R1--->(matrix(2,3,1,0,-2,0,1,3)) so we end with
a=-2
b=3
so X=(matrix(2,1,-2,3))
:
please re write equation 5 making it clear what their after
:
6)6.[1 -6 0] [1}
[0 1 -7] [X} =[4]
[3 0 2] [11]
In order to go from a 3x3 to a 3x1 X also has to be a 3x1
:
call X=(matrix(3,1,a,b,c))
:
a-6b=1.....eq 1
b-7c=4.....eq 2
3a-2c=11...eq 3
:
lets solve by substution method
:
revise eq 1 to a=1+6b and plug that value into eq 3
:
3(1+6b)-2c=11
:
3+18b-2c=11
:
18b-2c=8....eq 3 revised
b-7c=4....eq 2
:
multiply eq 2 by -18 and add the results to revised eq 3
:
18b-2c=8.......eq 3 revised
-18b+126c=-72..eq 2 revised
:
as you can see the b terms are eliminated. We are left with -2c+126c=8-72
:
124c=-64
:
c=-64/124=-32/62=-16/31
:
b-7(-16/31)=4
:
b+112/31=4...multiply by 31
:
31b+112=124
:
31b=12
:
b=12/31
:
a=1+6(12/31)
a=31/31+72/31
:
a=103/31
:
X=(matrix(3,1,103/31,12/31,-16/31))

Question 173807: Find matrix X: AX= B
1. A= [6,5] B= [18,49]
[4,-2] [-20,6]

2. A= [3,4] B= [10,-10]
[-3,-2] [-8,8]
: Find matrix X: AX= B
1. A= [6,5] B= [18,49]
[4,-2] [-20,6]

2. A= [3,4] B= [10,-10]
[-3,-2] [-8,8]

Answer by Mathtut(1329) About Me  (Show Source):
You can put this solution on YOUR website!
 
:
We must find the inverse of matrix A in order to solve for x
:
A= [6,5]
[4,-2]
:
take terms a[11]and a[22] and switch their positions. This is simply switching the elements on the main diagonal

take terms a[12]and a[21] and change those numbers to their opposites keeping there positions.
(matrix(2,2,-2,-5,-4,6))-revised matrix
:now we find the determinant of this matrix
:
product of the main diagonal minus the product of the off diagonal
:
-12-20=-32
:
we take that result and divide every element in the revised matrix and the result is our inverse matrix
:
(matrix(2,2,1/16,5/32,1/8,-3/16))
:
Now we have to multiply each side of the equation AX=B by the matrix A's inverse
On the left hand side we will end up with the indentity matrix multiplied by X which is equal to just X. So X=A^-1(B)
:
A= [6,5] B= [18,49]
[4,-2] [-20,6]
:
so
X=(matrix(2,2,1/16,5/32,1/8,-3/16))*(matrix(2,2,18,49,-20,6))---->
:
=(matrix(2,2,-2,4,6,5))
:
2) I will leave the details and steps of # 2 to you
:
the answer is (matrix(2,2,2,-2,1,-1))

Question 174388: Find the inverse of each matrix, if it exists...

1.. [-2 -1]
[10 7]

2..[-4 2]
[-5 1]

3.. [9 -3]
[-6 2]

4.. [3 4] [6]
[2 3] x=[5]

5..[1 -6 0] [1]
[0 1 -7]x=[4]
[3 0 2] [11]
: Find the inverse of each matrix, if it exists...

1.. [-2 -1]
[10 7]

2..[-4 2]
[-5 1]

3.. [9 -3]
[-6 2]

4.. [3 4] [6]
[2 3] x=[5]

5..[1 -6 0] [1]
[0 1 -7]x=[4]
[3 0 2] [11]

Answer by Mathtut(1329) About Me  (Show Source):
You can put this solution on YOUR website!
 
(matrix(2,2,-2,-1,10,7))
:
take terms a[11]and a[22] and switch their positions. This is simply switching the elements on the main diagonal 
 
take terms a[12]and a[21] and change those numbers to their opposites keeping there positions.

(matrix(2,2,7,1,-10,-2))
:now we find the determinant of this matrix
:
product of the main diagonal-product of the other diagonal
:
-14-(-10)=-4
:
we take that result and divide every element in the matrix and the result is our inverse matrix
:
(matrix(2,2,-7/4,-1/4,5/2,1/2))
the way you can check is to multiply the two together and see if your result is the identity matrix....if it is you can rest easy you have the correct answer.
:

:
:
:
2)and 3)
:
now I will let you do the steps to 2 and 3
:
answers to 2 is (matrix(2,2,1/6,-1/3,5/6,-2/3))
...........3 is no solution as the determinant = 0
:
4)(matrix(2,2,3,4,2,3))X or(matrix(2,1,a,b))=(matrix(2,1,6,5)))
3a+4b=6
2a+3b=5
:
(matrix(2,3,3,4,6,2,3,5))3R2-2R1(Row 2)---->(matrix(2,3,3,4,6,0,1,3))R1-4R2(row 1)---->(matrix(2,3,3,0,-6,0,1,3))1/3R1--->(matrix(2,3,1,0,-2,0,1,3)) so we end with 
a=-2
b=3
so X=(matrix(2,1,-2,3))
:
5) is done the same as 4 but this time you have 3 variables....have fun

Question 173474: Solve for Matrix X:
(matrix(2,2,-3,-14,2,9))X=(matrix(2,2,8,-4,0,-4))
: Solve for Matrix X:
(matrix(2,2,-3,-14,2,9))X=(matrix(2,2,8,-4,0,-4))

Answer by Edwin McCravy(2190) About Me  (Show Source):
You can put this solution on YOUR website!


(matrix(2,2,-3,-14,2,9))X=(matrix(2,2,8,-4,0,-4))

First find the inverse of (matrix(2,2,-3,-14,2,9)) by

1. find the determinant 

matrix(1,7,   abs(matrix(2,2,-3,-14,2,9)), '=', (-3)(9)-(-14)(2), '=', -27+28,'=',1)

2. Swap the elements is the upper left to lower right diagonal.
   Change the signs in the other diagonal.

(matrix(2,2,-9,14,2,3))


3. Divide the matrix through by the determinant

matrix(1,5,(matrix(2,2,-9,14,2,3)), '๗', 1, '=', (matrix(2,2,-9,14,2,3)) ) 

That is the inverse matrix. So left-multiply both sides
of the original equation by this inverse:

(matrix(2,2,-3,-14,2,9))X=(matrix(2,2,8,-4,0,-4))

(matrix(2,2,-9,14,2,3))(matrix(2,2,-3,-14,2,9))X=(matrix(2,2,-9,14,2,3))(matrix(2,2,8,-4,0,-4))


(matrix(2,2,1,0,0,1))X=(matrix(2,2,-72,-20,16,-20))

X=(matrix(2,2,-72,-20,16,-20))

Edwin

Question 174121: please give me the answers..
use a caret (^) to indicate the power. For example, 53 would be written as 5^3.
1. Write the equation of a polynomial that has zeros at –3 and 2.

Write each polynomial function in standard form. Then classify it by degree and by the number of terms.
2. n = 4m2 – m + 7m4
n = 4m3 + 4m – 2; cubic trinomial
n = 7m4 + 4m2 – m; quartic trinomial
n = 4m4 + 8m2 – m ; quartic trinomial
n = 3m3 + 2m – 5; cubic trinomial

3. f(t) = 4t + 3t3 + 2t – 7
f(t) = 3t3 + 6t – 7; cubic trinomial
f(t) = 2t3 + 4t – 1; cubic trinomial
f(t) = 5t3 + 2t – 7; cubic trinomial
f(t) = 7t3 + 3t – 4; cubic trinomial

4. f(r) = 5r + 7 + 2r2
f(r) = 8r3 + 5r + 1; cubic trinomial
f(r) = r2 + 5r + 7; quadratic trinomial
f(r) = 2r3 + 5r + 7; cubic trinomial
f(r) = 2r2 + 5r + 7; quadratic trinomial

For each function, determine the zeros and their multiplicity.
5. y = (x + 2)2(x – 5)4
–2, multiplicity 2; 5, multiplicity 4
2, multiplicity 2; 5, multiplicity 3
–2, multiplicity 4; 5, multiplicity 2
2, multiplicity 2; 7, multiplicity 4

6. y = (3x + 2)3(x – 5)5
4, multiplicity 2; 5, multiplicity 2
3, multiplicity 4; 2, multiplicity 4
, multiplicity 3; 5, multiplicity 5
2, multiplicity 3; 5, multiplicity 5

7. y = x2(x + 4)3(x – 1)
2, multiplicity 2; –4, multiplicity 2; 1, multiplicity 1
0, multiplicity 2; –4, multiplicity 3; 1, multiplicity 1
3, multiplicity 4; –3, multiplicity 2; 2, multiplicity 3
0, multiplicity 2; –3, multiplicity 2; 2, multiplicity 3


8. (x3 + 3x2 – x – 3) ๗ (x – 1)

10. Use synthetic division to find P(–3) for P(x) = –2x4 – 3x3 – x + 4.
: please give me the answers..
use a caret (^) to indicate the power. For example, 53 would be written as 5^3.
1. Write the equation of a polynomial that has zeros at –3 and 2.

Write each polynomial function in standard form. Then classify it by degree and by the number of terms.
2. n = 4m2 – m + 7m4
n = 4m3 + 4m – 2; cubic trinomial
n = 7m4 + 4m2 – m; quartic trinomial
n = 4m4 + 8m2 – m ; quartic trinomial
n = 3m3 + 2m – 5; cubic trinomial

3. f(t) = 4t + 3t3 + 2t – 7
f(t) = 3t3 + 6t – 7; cubic trinomial
f(t) = 2t3 + 4t – 1; cubic trinomial
f(t) = 5t3 + 2t – 7; cubic trinomial
f(t) = 7t3 + 3t – 4; cubic trinomial

4. f(r) = 5r + 7 + 2r2
f(r) = 8r3 + 5r + 1; cubic trinomial
f(r) = r2 + 5r + 7; quadratic trinomial
f(r) = 2r3 + 5r + 7; cubic trinomial
f(r) = 2r2 + 5r + 7; quadratic trinomial

For each function, determine the zeros and their multiplicity.
5. y = (x + 2)2(x – 5)4
–2, multiplicity 2; 5, multiplicity 4
2, multiplicity 2; 5, multiplicity 3
–2, multiplicity 4; 5, multiplicity 2
2, multiplicity 2; 7, multiplicity 4

6. y = (3x + 2)3(x – 5)5
4, multiplicity 2; 5, multiplicity 2
3, multiplicity 4; 2, multiplicity 4
, multiplicity 3; 5, multiplicity 5
2, multiplicity 3; 5, multiplicity 5

7. y = x2(x + 4)3(x – 1)
2, multiplicity 2; –4, multiplicity 2; 1, multiplicity 1
0, multiplicity 2; –4, multiplicity 3; 1, multiplicity 1
3, multiplicity 4; –3, multiplicity 2; 2, multiplicity 3
0, multiplicity 2; –3, multiplicity 2; 2, multiplicity 3


8. (x3 + 3x2 – x – 3) ๗ (x – 1)

10. Use synthetic division to find P(–3) for P(x) = –2x4 – 3x3 – x + 4.

Answer by stanbon(19714) About Me  (Show Source):
You can put this solution on YOUR website!
1. Write the equation of a polynomial that has zeros at –3 and 2.
Equation: f(x) = (x+3)(x-2)
---------------------------------------
Write each polynomial function in standard form. Then classify it by degree and by the number of terms.
2. n = 4m2 – m + 7m4
n = 4m3 + 4m – 2; cubic trinomial
n = 7m4 + 4m2 – m; quartic trinomial---Correct
n = 4m4 + 8m2 – m ; quartic trinomial
n = 3m3 + 2m – 5; cubic trinomial
-----------------------------------------
3. f(t) = 4t + 3t3 + 2t – 7
f(t) = 3t3 + 6t – 7; cubic trinomial-----Correct
f(t) = 2t3 + 4t – 1; cubic trinomial
f(t) = 5t3 + 2t – 7; cubic trinomial
f(t) = 7t3 + 3t – 4; cubic trinomial
------------------------------------------
4. f(r) = 5r + 7 + 2r2
f(r) = 8r3 + 5r + 1; cubic trinomial
f(r) = r2 + 5r + 7; quadratic trinomial
f(r) = 2r3 + 5r + 7; cubic trinomial
f(r) = 2r2 + 5r + 7; quadratic trinomial----Correct
------------------------------------------
For each function, determine the zeros and their multiplicity.
5. y = (x + 2)^2(x – 5)^4
–2, multiplicity 2; 5, multiplicity 4----Correct
2, multiplicity 2; 5, multiplicity 3
–2, multiplicity 4; 5, multiplicity 2
2, multiplicity 2; 7, multiplicity 4
------------------------------------------
6. y = (3x + 2)^3(x – 5)^5
4, multiplicity 2; 5, multiplicity 2
3, multiplicity 4; 2, multiplicity 4
-2/3, multiplicity 3; 5, multiplicity 5----Correct
2, multiplicity 3; 5, multiplicity 5
-------------------------------------------
7. y = x^2(x + 4)^3(x – 1)
2, multiplicity 2; –4, multiplicity 2; 1, multiplicity 1
0, multiplicity 2; –4, multiplicity 3; 1, multiplicity 1----Correct
3, multiplicity 4; –3, multiplicity 2; 2, multiplicity 3
0, multiplicity 2; –3, multiplicity 2; 2, multiplicity 3
-------------------------------------------

8. (x^3 + 3x^2 – x – 3) ๗ (x – 1)
1)....1....3....-1....-3
.......1....4.....3....|..0
Quotient: x^2 + 4x + 3
Remainder: 0
--------------------------------------------
10. Use synthetic division to find P(–3) for P(x) = –2x^4 – 3x^3 – x + 4
-3)....-2....-3....-1....4
.........-2....3.....-8..|..28
Quotient: -2x^2 + 3x -8
Remainder: 28
====================
Cheers,
Stan H.

Question 173944: at a local farmers market,Jane sold 27 squash,31 tomatoes,24 peppers,and 18 melons.Jose sold 48 squash,72 tomatoes,61 peppers, and 25 melons.
a)Create a 2x4 matrix of this data.Name this matrix P.
b)What is the address of the number of peppers that jane sold?
c)What is the address of the data stored in the second row and first column?What does this entry represent?
d)Could you have created a matrix with different dimensions from the created part a?
: at a local farmers market,Jane sold 27 squash,31 tomatoes,24 peppers,and 18 melons.Jose sold 48 squash,72 tomatoes,61 peppers, and 25 melons.
a)Create a 2x4 matrix of this data.Name this matrix P.
b)What is the address of the number of peppers that jane sold?
c)What is the address of the data stored in the second row and first column?What does this entry represent?
d)Could you have created a matrix with different dimensions from the created part a?

Answer by Edwin McCravy(2190) About Me  (Show Source):
You can put this solution on YOUR website!
at a local farmers market,Jane sold 27 squash,31 tomatoes,24 peppers,and 18 melons.Jose sold 48 squash,72 tomatoes,61 peppers, and 25 melons.
a)Create a 2x4 matrix of this data.Name this matrix P.

matrix(3,3,'','','',P, '=', matrix(3,7, 

'', '', squash, tomatoes, peppers, melons, '',
Jane, '[', 27, 31, 24, 18, ']', Jose, '[', 48, 72, 61, 25, ']'),'','','')

Or if your teacher doesn't want headings, then just use

(matrix(2,4,27,31,24,18,48,72,61,25))



b)What is the address of the number of peppers that jane sold?

1,3, or "Row 1, Column 3"

c)What is the address of the data stored in the second row and first column?

2,1

What does this entry represent?

The number of squash that Jose sold.


d)Could you have created a matrix with different dimensions from the created part a?

Yes, this 4x2 matrix:

matrix(5,5, '', '',  Jane, Jose, '',
                squash, '[', 27,    48,   ']',
                tomatoes,  '[', 31,    72,   ']',
                peppers, '[', 24,    61,   ']',
                melons, '[', 18,    25,   ']') 

or without headings  (matrix(4,2,27,48,31,72,24,61,18,25)) 

Edwin

Question 172008: find the inverse of matrix.

1. (matrix(2,2,2, -1, 10, 7))
2. (matrix(2,2,-4,2, -5, 1))
3. (matrix(2,2,9, -3, -6, 2))
: find the inverse of matrix.

1. (matrix(2,2,2, -1, 10, 7))
2. (matrix(2,2,-4,2, -5, 1))
3. (matrix(2,2,9, -3, -6, 2))

Answer by Edwin McCravy(2190) About Me  (Show Source):