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Exponential-and-logarithmic-functions/274779: Can someone please explain why logbx/ logby does not equal logbx - logby?
1 solutions

Answer 200502 by jim_thompson5910(28536) About Me  on 2010-02-27 00:20:19 (Show Source):
You can put this solution on YOUR website!
To prove something false, we usually resort to a counterexample. A counterexample is an explicit example in which proves a theorem or equation false (usually by a contradiction of some sort).

So let's say that x=b and y=b. This would then mean that


Now plug x=b and y=b into log%28b%2C%28x%29%29-log%28b%2C%28y%29%29 to get log%28b%2C%28x%29%29-log%28b%2C%28y%29%29=log%28b%2C%28b%29%29-log%28b%2C%28b%29%29=1-1=0


So in short, log%28b%2C%28x%29%29%2Flog%28b%2C%28y%29%29=1 and log%28b%2C%28x%29%29-log%28b%2C%28y%29%29=0 when x=b and y=b.


Clearly 1%3C%3E0 which means that log%28b%2C%28x%29%29%2Flog%28b%2C%28y%29%29%3C%3Elog%28b%2C%28x%29%29-log%28b%2C%28y%29%29 when x=b and y=b.

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

Here's another way of looking at it.


By the change of base formula, log%28b%2C%28x%29%29%2Flog%28b%2C%28y%29%29=log%28y%2C%28x%29%29

By another identity, log%28b%2C%28x%29%29-log%28b%2C%28y%29%29=log%28b%2C%28x%2Fy%29%29


So let's assume that log%28b%2C%28x%29%29%2Flog%28b%2C%28y%29%29=log%28b%2C%28x%29%29-log%28b%2C%28y%29%29. If this is the case, then log%28y%2C%28x%29%29=log%28b%2C%28x%2Fy%29%29


Equate the bases and arguments to get y=b and x=x%2Fy. The second equation simplifies to 1=1%2Fb. Solve for b to get b=1.


Now if b=1, this means that which is impossible (you can't divide by zero).


Points-lines-and-rays/274776: I am having a hard time with my Geomarty homework I would really like if i were to get some kind of help. The question on the homework says...
1.Draw the following triangle A(-3,2) B(9,2) C(3,-6)
1 solutions

Answer 200500 by jim_thompson5910(28536) About Me  on 2010-02-27 00:01:21 (Show Source):
You can put this solution on YOUR website!
Plot the 1st point A(-3,2)


Plot the 2nd point B(9,2)


Plot the 3rd point C(3,-6)



Now connect the points to plot the triangle:




Points-lines-and-rays/274778: Whats the distance between (4,4) and (7,8)
1 solutions

Answer 200499 by jim_thompson5910(28536) About Me  on 2010-02-26 23:51:12 (Show Source):
You can put this solution on YOUR website!
Note: is the first point . So this means that x%5B1%5D=4 and y%5B1%5D=4.
Also, is the second point . So this means that x%5B2%5D=7 and y%5B2%5D=8.


d=sqrt%28%28x%5B1%5D-x%5B2%5D%29%5E2%2B%28y%5B1%5D-y%5B2%5D%29%5E2%29 Start with the distance formula.


d=sqrt%28%284-7%29%5E2%2B%284-8%29%5E2%29 Plug in x%5B1%5D=4, x%5B2%5D=7, y%5B1%5D=4, and y%5B2%5D=8.


d=sqrt%28%28-3%29%5E2%2B%284-8%29%5E2%29 Subtract 7 from 4 to get -3.


d=sqrt%28%28-3%29%5E2%2B%28-4%29%5E2%29 Subtract 8 from 4 to get -4.


d=sqrt%289%2B%28-4%29%5E2%29 Square -3 to get 9.


d=sqrt%289%2B16%29 Square -4 to get 16.


d=sqrt%2825%29 Add 9 to 16 to get 25.


d=5 Take the square root of 25 to get 5.


So our answer is d=5


So the distance between the two points is 5 units.


Graphs/274760: Evaluate f(x)= 4x^2 - 2 for f(1/2)
1 solutions

Answer 200498 by jim_thompson5910(28536) About Me  on 2010-02-26 23:49:56 (Show Source):
You can put this solution on YOUR website!
f%28x%29=4x%5E2-2 Start with the given equation.


f%281%2F2%29=4%281%2F2%29%5E2-2 Plug in x=1%2F2.


f%281%2F2%29=4%281%2F4%29-2 Square 1%2F2 to get 1%2F4.


f%281%2F2%29=1-2 Multiply 4 and 1%2F4 to get 1.


f%281%2F2%29=-1 Combine like terms.


Linear-equations/274739: Find the equation of the line through the points (-3,-1) and (-9,-6)
1 solutions

Answer 200469 by jim_thompson5910(28536) About Me  on 2010-02-26 20:14:43 (Show Source):
You can put this solution on YOUR website!
First let's find the slope of the line through the points and


Note: is the first point . So this means that x%5B1%5D=-3 and y%5B1%5D=-1.
Also, is the second point . So this means that x%5B2%5D=-9 and y%5B2%5D=-6.


m=%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29 Start with the slope formula.


m=%28-6--1%29%2F%28-9--3%29 Plug in y%5B2%5D=-6, y%5B1%5D=-1, x%5B2%5D=-9, and x%5B1%5D=-3


m=%28-5%29%2F%28-9--3%29 Subtract -1 from -6 to get -5


m=%28-5%29%2F%28-6%29 Subtract -3 from -9 to get -6


m=5%2F6 Reduce


So the slope of the line that goes through the points and is m=5%2F6

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

Now remember that the general slope intercept equation is y=mx%2Bb where 'm' is the slope of the line and 'b' is the y-intercept. We can use this general equation to find the equation of the line.

Since the line goes through the point (-3,-1), this means that x=-3 and y=-1. In addition, we know that the slope is m=5%2F6. So we can use these values to solve for 'b'.


y=mx%2Bb Start with the general slope-intercept equation.


-1=%285%2F6%29%28-3%29%2Bb Plug in x=-3, y=-1 and m=5%2F6


-1=-15%2F6%2Bb Multiply.


-1=-5%2F2%2Bb Reduce.


-1%2B5%2F2=b Add 5%2F2 to both sides to isolate 'b'


3%2F2=b Combine like terms.


So the value of 'b' is b=3%2F2


Since m=5%2F6 and b=3%2F2, we can plug these values into y=mx%2Bb to get y=%285%2F6%29x%2B3%2F2


======================================================================
Answer:

So the equation of the line in slope-intercept form through the points (-3,-1) and (-9,-6) is y=%285%2F6%29x%2B3%2F2


Polynomials-and-rational-expressions/274710: Find the quotient of the polynomials.
(3x^4-5x^3+2x-7) / (x-5)
1 solutions

Answer 200449 by jim_thompson5910(28536) About Me  on 2010-02-26 19:24:07 (Show Source):
You can put this solution on YOUR website!
Let's use polynomial long division to get



So this means that %283x%5E4-5x%5E3%2B2x-7%29%2F%28x-5%29=3x%5E3%2B10x%5E2%2B50x%2B252%2B1253%2F%28x-5%29


Functions/274719: Determine whether the correspondence is a function.
Celebrity~~~~~~~~~~~~~~~~ Birthday

Sigourney Weaver~~~~~~~~~~~ October 8
Jesse Jackson~~~~~~~~~~~~ October 8
Chevy Chase ~~~~~~~~~~~~~~ October 8

Muhammad Ali~~~~~~~~~~~~January 17
Jim Carrey~~~~~~~~~~~~~~January 17

Thank you for your help!
1 solutions

Answer 200447 by jim_thompson5910(28536) About Me  on 2010-02-26 19:19:26 (Show Source):
You can put this solution on YOUR website!
Since each celebrity has ONLY ONE birthday, this means that each input (celebrity) has ONLY ONE output (birthday). So this relation is a function.



Linear-equations/274720: I need to find an equation of the line containing the given pair of points; (-3,-1) and (-9,-6). The equation of the line in the slope-intercept is y=?
m=y2-y1= -6-(-1)= -5
x2-x1 -9-(-3) -6
y-(-1)=m(x-x1)
y-(-1)=-5(x-(-3))
-6
y-(-1)=-5x-5
-6 2
y=-5 -3
6x 2
Apparently I did this wrong somewhere and I am not sure what I did wrong. Can someone help me please.
1 solutions

Answer 200446 by jim_thompson5910(28536) About Me  on 2010-02-26 19:17:54 (Show Source):
You can put this solution on YOUR website!

First let's find the slope of the line through the points and


Note: is the first point . So this means that x%5B1%5D=-3 and y%5B1%5D=-1.
Also, is the second point . So this means that x%5B2%5D=-9 and y%5B2%5D=-6.


m=%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29 Start with the slope formula.


m=%28-6--1%29%2F%28-9--3%29 Plug in y%5B2%5D=-6, y%5B1%5D=-1, x%5B2%5D=-9, and x%5B1%5D=-3


m=%28-5%29%2F%28-9--3%29 Subtract -1 from -6 to get -5


m=%28-5%29%2F%28-6%29 Subtract -3 from -9 to get -6


m=5%2F6 Reduce


So the slope of the line that goes through the points and is m=5%2F6


Now let's use the point slope formula:


y-y%5B1%5D=m%28x-x%5B1%5D%29 Start with the point slope formula


y--1=%285%2F6%29%28x--3%29 Plug in m=5%2F6, x%5B1%5D=-3, and y%5B1%5D=-1


y--1=%285%2F6%29%28x%2B3%29 Rewrite x--3 as x%2B3


y%2B1=%285%2F6%29%28x%2B3%29 Rewrite y--1 as y%2B1


y%2B1=%285%2F6%29x%2B%285%2F6%29%283%29 Distribute


y%2B1=%285%2F6%29x%2B5%2F2 Multiply


y=%285%2F6%29x%2B5%2F2-1 Subtract 1 from both sides.


y=%285%2F6%29x%2B3%2F2 Combine like terms. note: If you need help with fractions, check out this solver.


So the equation that goes through the points and is y=%285%2F6%29x%2B3%2F2


Radicals/274702: how to write an equivalent expression using radical notation for
(16a^6)^3/4
1 solutions

Answer 200432 by jim_thompson5910(28536) About Me  on 2010-02-26 18:09:34 (Show Source):
You can put this solution on YOUR website!
Recall that x%5E%28m%2Fn%29%5E%27%27=root%28n%2Cx%5Em%29


This means that %2816a%5E6%29%5E%283%2F4%29%5E%27%27=root%284%2C%2816a%5E6%29%5E3%29


We could optionally cube 16a%5E6 to get 4096a%5E18 which would mean that %2816a%5E6%29%5E%283%2F4%29%5E%27%27=root%284%2C4096a%5E18%29


expressions/274703: Evaluate the factorial expression
(n+5)!/n+5
1 solutions

Answer 200429 by jim_thompson5910(28536) About Me  on 2010-02-26 18:06:44 (Show Source):
You can put this solution on YOUR website!
Since %28n%2B5%29%21=%28n%2B5%29%28n%2B5-1%29%21=%28n%2B5%29%28n%2B4%29%21, this means that


In other words, %28n%2B5%29%21%2F%28n%2B5%29=%28n%2B4%29%21


Graphs/274663: what is the euclidean distance from the point (3,5) to the line y=2x
1 solutions

Answer 200418 by jim_thompson5910(28536) About Me  on 2010-02-26 16:16:50 (Show Source):
You can put this solution on YOUR website!
Solved by pluggable solver: Finding a distance between a point given by coordinates (x, y) and a line given by equation y=ax+b
We want to find the perpendicular distance between a point given by coordinates (3,5)
and a line given by equation y=2%2Ax%2B0

First, let's draw a diagram of general situation with point P (xo, yo) and
line L: y= a.x + b. The required distance is PC. (in the diagram below)





Methodology
We will first find the vertices of the triangle in order to get the side lengths and then by applying
Sine Rule on right angle triangle PAB and PBC we will calculate the desired distance PC.


Step1
Calculation of the vertices of triangle PAB:

Draw a vertical line passing through the point 'P'. This line x=3 will cut the given line 'L'
at point 'A'. The X coordinate of A(x1) will be same as xo=3. To find the Y-coordinate of
'A' we will use the fact that point 'A' lies on the given line 'L' and satisfies the equation
of the line 'L'
.
Now, plug this x1=3 in to the equation of line: y=2*x+0
y1=2%2A3+%2B0
y1=6

Hence, Point (A)(x1=3,y1=6)


Similarly,
Draw a horizontal line passing through the point 'P'. This line y=5 will cut the given line 'L'
at point 'B'. The Y coordinate of B(y2) will be same as yo=5. To find the X-coordinate of
B we will use the fact that point 'B' lies on the given line 'L' and satisfies the equation
of the line 'L'
.
Now, plug this y2=5 in to the equation of line: y=2*x+0
5=2%2Ax2%2B0
x2=+%285-0%29%2F2
x2=2.5

Hence, Point (B)(x2=2.5,y2=5)


Now, we have all the vertices of the triangle PAB


Step2
Calculation of the side lengths using distance formula:

d=sqrt%28%28x1-x2%29%5E2+%2B+%28y1-y2%29%5E2%29


Hence, The side lengths PA, PB and AB are
PA=1
PB=0.5
AB=1.11803398874989


Step3
Apply Sine rule on common angle B in triangle PAB and triangle PBC.
Both triangle PAB and triangle PBC are right angle triangle and points 'A', 'B' and 'C' lay on the given line L.

Sin%28B%29=+AP%2FAB=PC%2FBP

PC=%28AP%2ABP%29%2FAB=+0.447213595499958


PC is the required perpendicular distance of the point P (3, 5) from line given
lineL1: y=2*x+0.


For better understanding of this concept, look at the Lesson based on the above concept.
Lesson




So the distance is approximately 0.447 units.


Matrices-and-determiminant/274496: Use Cramer's rule to solve the systems:
1. 2x-9y-z=-72
x+3y+4z=51
-6x+y+z=-4

2. 4x+6y=14
2x+y=-3
1 solutions

Answer 200314 by jim_thompson5910(28536) About Me  on 2010-02-26 01:40:09 (Show Source):
You can put this solution on YOUR website!
# 1

Solved by pluggable solver: Using Cramer's Rule to Solve Systems with 3 variables







First let A=%28matrix%283%2C3%2C2%2C-9%2C-1%2C1%2C3%2C4%2C-6%2C1%2C1%29%29. This is the matrix formed by the coefficients of the given system of equations.


Take note that the right hand values of the system are -72, 51, and -4 and they are highlighted here:




These values are important as they will be used to replace the columns of the matrix A.




Now let's calculate the the determinant of the matrix A to get abs%28A%29=204. To save space, I'm not showing the calculations for the determinant. However, if you need help with calculating the determinant of the matrix A, check out this solver.



Notation note: abs%28A%29 denotes the determinant of the matrix A.



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



Now replace the first column of A (that corresponds to the variable 'x') with the values that form the right hand side of the system of equations. We will denote this new matrix A%5Bx%5D (since we're replacing the 'x' column so to speak).






Now compute the determinant of A%5Bx%5D to get abs%28A%5Bx%5D%29=612. Again, as a space saver, I didn't include the calculations of the determinant. Check out this solver to see how to find this determinant.



To find the first solution, simply divide the determinant of A%5Bx%5D by the determinant of A to get: x=%28abs%28A%5Bx%5D%29%29%2F%28abs%28A%29%29=%28612%29%2F%28204%29=3



So the first solution is x=3




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


We'll follow the same basic idea to find the other two solutions. Let's reset by letting A=%28matrix%283%2C3%2C2%2C-9%2C-1%2C1%2C3%2C4%2C-6%2C1%2C1%29%29 again (this is the coefficient matrix).




Now replace the second column of A (that corresponds to the variable 'y') with the values that form the right hand side of the system of equations. We will denote this new matrix A%5By%5D (since we're replacing the 'y' column in a way).






Now compute the determinant of A%5By%5D to get abs%28A%5By%5D%29=1632.



To find the second solution, divide the determinant of A%5By%5D by the determinant of A to get: y=%28abs%28A%5By%5D%29%29%2F%28abs%28A%29%29=%281632%29%2F%28204%29=8



So the second solution is y=8




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





Let's reset again by letting A=%28matrix%283%2C3%2C2%2C-9%2C-1%2C1%2C3%2C4%2C-6%2C1%2C1%29%29 which is the coefficient matrix.



Replace the third column of A (that corresponds to the variable 'z') with the values that form the right hand side of the system of equations. We will denote this new matrix A%5Bz%5D






Now compute the determinant of A%5Bz%5D to get abs%28A%5Bz%5D%29=1224.



To find the third solution, divide the determinant of A%5Bz%5D by the determinant of A to get: z=%28abs%28A%5Bz%5D%29%29%2F%28abs%28A%29%29=%281224%29%2F%28204%29=6



So the third solution is z=6




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

Final Answer:




So the three solutions are x=3, y=8, and z=6 giving the ordered triple (3, 8, 6)




Note: there is a lot of work that is hidden in finding the determinants. Take a look at this 3x3 Determinant Solver to see how to get each determinant.





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

# 2

Solved by pluggable solver: Using Cramer's Rule to Solve Systems with 2 variables



system%284%2Ax%2B6%2Ay=14%2C2%2Ax%2B1%2Ay=-3%29



First let A=%28matrix%282%2C2%2C4%2C6%2C2%2C1%29%29. This is the matrix formed by the coefficients of the given system of equations.


Take note that the right hand values of the system are 14 and -3 which are highlighted here:
system%284%2Ax%2B6%2Ay=highlight%2814%29%2C2%2Ax%2B1%2Ay=highlight%28-3%29%29



These values are important as they will be used to replace the columns of the matrix A.




Now let's calculate the the determinant of the matrix A to get abs%28A%29=%284%29%281%29-%286%29%282%29=-8. Remember that the determinant of the 2x2 matrix A=%28matrix%282%2C2%2Ca%2Cb%2Cc%2Cd%29%29 is abs%28A%29=ad-bc. If you need help with calculating the determinant of any two by two matrices, then check out this solver.



Notation note: abs%28A%29 denotes the determinant of the matrix A.



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



Now replace the first column of A (that corresponds to the variable 'x') with the values that form the right hand side of the system of equations. We will denote this new matrix A%5Bx%5D (since we're replacing the 'x' column so to speak).


A%5Bx%5D=%28matrix%282%2C2%2Chighlight%2814%29%2C6%2Chighlight%28-3%29%2C1%29%29



Now compute the determinant of A%5Bx%5D to get abs%28A%5Bx%5D%29=%2814%29%281%29-%286%29%28-3%29=32. Once again, remember that the determinant of the 2x2 matrix A=%28matrix%282%2C2%2Ca%2Cb%2Cc%2Cd%29%29 is abs%28A%29=ad-bc



To find the first solution, simply divide the determinant of A%5Bx%5D by the determinant of A to get: x=%28abs%28A%5Bx%5D%29%29%2F%28abs%28A%29%29=%2832%29%2F%28-8%29=-4



So the first solution is x=-4




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


We'll follow the same basic idea to find the other solution. Let's reset by letting A=%28matrix%282%2C2%2C4%2C6%2C2%2C1%29%29 again (this is the coefficient matrix).




Now replace the second column of A (that corresponds to the variable 'y') with the values that form the right hand side of the system of equations. We will denote this new matrix A%5By%5D (since we're replacing the 'y' column in a way).


A%5Bx%5D=%28matrix%282%2C2%2C4%2Chighlight%2814%29%2C2%2Chighlight%28-3%29%29%29



Now compute the determinant of A%5By%5D to get abs%28A%5By%5D%29=%284%29%28-3%29-%2814%29%282%29=-40.



To find the second solution, divide the determinant of A%5By%5D by the determinant of A to get: y=%28abs%28A%5By%5D%29%29%2F%28abs%28A%29%29=%28-40%29%2F%28-8%29=5



So the second solution is y=5




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

Final Answer:




So the solutions are x=-4 and y=5 giving the ordered pair (-4, 5)




Once again, Cramer's Rule is dependent on determinants. Take a look at this 2x2 Determinant Solver if you need more practice with determinants.




real-numbers/274513: Hello,
I am having a question on 1 problem for my online Algebra class that just are not clicking in my head. I have tried to do them several times. I would really appreciate if you could help with these two :)
Thank You
it read a-2/5 + a-3/4 = 6/5





1 solutions

Answer 200312 by jim_thompson5910(28536) About Me  on 2010-02-26 01:37:15 (Show Source):
You can put this solution on YOUR website!
I'm assuming that the problem is a-2%2F5%2Ba-3%2F4=6%2F5


a-2%2F5%2Ba-3%2F4=6%2F5 Start with the given equation.


20%28a-2%2Fcross%285%29%2Ba-3%2Fcross%284%29%29=20%286%2Fcross%285%29%29 Multiply both sides by the LCD 20 to clear any fractions.


20a-8%2B20a-15=24 Distribute and multiply.


40a-23=24 Combine like terms on the left side.


40a=24%2B23 Add 23 to both sides.


40a=47 Combine like terms on the right side.


a=%2847%29%2F%2840%29 Divide both sides by 40 to isolate a.


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

Answer:

So the solution is a=47%2F40 which approximates to a=1.175.


Expressions-with-variables/274504: After you show me how to solve this question I can help my son complete the rest. Luke has $5 more than sam. Together they have $73. How much does each have?
1 solutions

Answer 200306 by jim_thompson5910(28536) About Me  on 2010-02-26 00:25:45 (Show Source):
You can put this solution on YOUR website!
Let x = amount that luke has and y = amount that sam has

So "Luke has $5 more than sam" means that x=y%2B5 and "Together they have $73" tells us that x%2By=73


x%2By=73 Start with the given equation.


y%2B5%2By=73 Plug in x=y%2B5


2y%2B5=73 Combine like terms on the left side.


2y=73-5 Subtract 5 from both sides.


2y=68 Combine like terms on the right side.


y=%2868%29%2F%282%29 Divide both sides by 2 to isolate y.


y=34 Reduce.


So this means that sam has $34


x=y%2B5 Go back to the first equation


x=34%2B5 Plug in y=34


x=39 Add


So this means that Luke has $39


Polynomials-and-rational-expressions/274509: I can't find two numbers that multiplied give me negative 270 and added give me negative 49
1 solutions

Answer 200304 by jim_thompson5910(28536) About Me  on 2010-02-26 00:20:11 (Show Source):
You can put this solution on YOUR website!
Let's list all of the factors of -270 (the product needed).


Factors of -270:
1,2,3,5,6,9,10,15,18,27,30,45,54,90,135,270
-1,-2,-3,-5,-6,-9,-10,-15,-18,-27,-30,-45,-54,-90,-135,-270


Note: list the negative of each factor. This will allow us to find all possible combinations.


These factors pair up and multiply to -270.
1*(-270) = -270
2*(-135) = -270
3*(-90) = -270
5*(-54) = -270
6*(-45) = -270
9*(-30) = -270
10*(-27) = -270
15*(-18) = -270
(-1)*(270) = -270
(-2)*(135) = -270
(-3)*(90) = -270
(-5)*(54) = -270
(-6)*(45) = -270
(-9)*(30) = -270
(-10)*(27) = -270
(-15)*(18) = -270

Now let's add up each pair of factors to see if one pair adds to -49:


First NumberSecond NumberSum
1-2701+(-270)=-269
2-1352+(-135)=-133
3-903+(-90)=-87
5-545+(-54)=-49
6-456+(-45)=-39
9-309+(-30)=-21
10-2710+(-27)=-17
15-1815+(-18)=-3
-1270-1+270=269
-2135-2+135=133
-390-3+90=87
-554-5+54=49
-645-6+45=39
-930-9+30=21
-1027-10+27=17
-1518-15+18=3



From the table, we can see that the two numbers 5 and -54 add to -49. Since each pair multiplies to -270, this means that 5 and -54 also multiply to -270.


So the two numbers 5 and -54 both add to -49 and multiply to -270.


Inequalities/274500: How do I graph this inequality and what is the solution?
y < 4x - 3
x - y _>_ -12
Note: _>_ Means that the sign is underline, meaning "Or equal to."
How would I graph this inequality and what is the estimated point of solution?
I already know that one line produces as true while the other produces a false answer when I substitute it with (0, 0). This leaves me stumped on where to shade, since it is an inequality.
I also need to include a point of solution, and this inequality doesn't appear to have any...
Thank you for any help.
1 solutions

Answer 200302 by jim_thompson5910(28536) About Me  on 2010-02-26 00:16:26 (Show Source):
You can put this solution on YOUR website!
Start with the given system of inequalities
y+%3C+4x+-+3
x-y%3E=-12

In order to graph this system of inequalities, we need to graph each inequality one at a time.


First lets graph the first inequality y+%3C+4x+-+3
In order to graph y+%3C+4x+-+3, we need to graph the equation y+=+4x+-+3 (just replace the inequality sign with an equal sign).
So lets graph the line y+=+4x+-+3 (note: if you need help with graphing, check out this solver)
+graph%28+500%2C+500%2C+-20%2C+20%2C+-20%2C+20%2C+4x-3%29+ graph of y=4x+-+3
Now lets pick a test point, say (0,0). Any point will work, (just make sure the point doesn't lie on the line) but this point is the easiest to work with. Now evaluate the inequality y+%3C+4x+-+3 with the test point

Substitute (0,0) into the inequality


0+%3C+4%280%29+-+3 Plug in x=0 and y=0


0%3C-3 Simplify


Since this inequality is not true, we do not shade the entire region that contains (0,0). So this means we shade the region that is on the opposite side of the line
Graph of -4x%2By%3C-3 with the boundary (which is the line -4x%2By=-3 in red) and the shaded region (in green)
(note: since the inequality contains a less-than sign, this means the boundary is excluded. This means the solid red line is really a dashed line)
---------------------------------------------------------------


Now lets graph the second inequality x-y%3E=-12
In order to graph x-y%3E=-12, we need to graph the equation x-y=-12 (just replace the inequality sign with an equal sign).
So lets graph the line x-y=-12 (note: if you need help with graphing, check out this
solver)
+graph%28+500%2C+500%2C+-20%2C+20%2C+-20%2C+20%2C+x%2B12%29+ graph of x-y=-12
Now lets pick a test point, say (0,0). Any point will work, (just make sure the point doesn't lie on the line) but this point is the easiest to work with. Now evaluate the inequality x-y%3E=-12 with the test point

Substitute (0,0) into the inequality


%280%29-%280%29%3E=-12 Plug in x=0 and y=0


0%3E=-12 Simplify



Since this inequality is true, we simply shade the entire region that contains (0,0)
Graph of x-y%3E=-12 with the boundary (which is the line x-y=-12 in red) and the shaded region (in green)

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


So we essentially have these 2 regions:

Region #1
Graph of -4x%2By%3C-3


Region #2
Graph of x-y%3E=-12




When these inequalities are graphed on the same coordinate system, the regions overlap to produce this region. It's a little hard to see, but after evenly shading each region, the intersecting region will be the most shaded in.







Here is a cleaner look at the intersection of regions




Here is the intersection of the 2 regions represented by the series of dots


Matrices-and-determiminant/274498: Evaluate the determinant:
|3 3 4|
|6 1 2|
|3 2 2|
1 solutions

Answer 200301 by jim_thompson5910(28536) About Me  on 2010-02-26 00:06:00 (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:

%28matrix%283%2C3%2Ca%2Cb%2Cc%2Cd%2Ce%2Cf%2Cg%2Ch%2Ci%29%29

the determinant is:

Which further breaks down to:



Note: abs%28matrix%282%2C2%2Ce%2Cf%2Ch%2Ci%29%29, abs%28matrix%282%2C2%2Cd%2Cf%2Cg%2Ci%29%29 and abs%28matrix%282%2C2%2Cd%2Ce%2Cg%2Ch%29%29 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 %28matrix%283%2C3%2C3%2C3%2C4%2C6%2C1%2C2%2C3%2C2%2C2%29%29, we can see that a=3, b=3, c=4, d=6, e=1, f=2, g=3, h=2, and i=2

Start with the general 3x3 determinant.

Plug in the given values (see above)

Multiply

Subtract

abs%28matrix%283%2C3%2C3%2C3%2C4%2C6%2C1%2C2%2C3%2C2%2C2%29%29=-6-18%2B36 Multiply

abs%28matrix%283%2C3%2C3%2C3%2C4%2C6%2C1%2C2%2C3%2C2%2C2%29%29=12 Combine like terms.


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


Answer:

So abs%28matrix%283%2C3%2C3%2C3%2C4%2C6%2C1%2C2%2C3%2C2%2C2%29%29=12, which means that the determinant of the matrix %28matrix%283%2C3%2C3%2C3%2C4%2C6%2C1%2C2%2C3%2C2%2C2%29%29 is 12


Polynomials-and-rational-expressions/274372: Thanks in advance for your help...
Here's my problem-
The product of two consecutive positive odd integers is 38 less than the square of the greater integer. Find the integers.
Now I know that product means mulitiplication so I thought I set the problem up as such:
x(x+2)= (x+2)^2-38.
Would this be correct?
1 solutions

Answer 200250 by jim_thompson5910(28536) About Me  on 2010-02-25 19:37:47 (Show Source):
You can put this solution on YOUR website!
You have the right equation. Now let's solve for 'x'.

x%28x%2B2%29=+%28x%2B2%29%5E2-38 Start with the given equation.


x%5E2%2B2x=+%28x%2B2%29%5E2-38 Distribute


x%5E2%2B2x=+x%5E2%2B4x%2B4-38 FOIL


2x=+4x%2B4-38 Subtract x%5E2 from both sides.


2x=4x-34 Combine like terms on the right side.


2x-4x=-34 Subtract 4x from both sides.


-2x=-34 Combine like terms on the left side.


x=%28-34%29%2F%28-2%29 Divide both sides by -2 to isolate x.


x=17 Reduce.


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

Answer:

So the solution is x=17


So the two numbers are 17 and 19.


Polynomials-and-rational-expressions/274329: x^2+10x-128. I've had this problem a few times now (I'm a tutor myself) and it asks to solve for x. I just cannot factor this. Please help me refresh my algebra skills and help me find a way to solve for x on this one. Thank you.
1 solutions

Answer 200222 by jim_thompson5910(28536) About Me  on 2010-02-25 18:19:03 (Show Source):
You can put this solution on YOUR website!
For more factoring help, check out this quadratic formula solver.

Solved by pluggable solver: Factoring using the AC method (Factor by Grouping)
In order to factor x%5E2%2B10%2Ax-128, first multiply the leading coefficient 1 and the last term -128 to get -128. Now we need to ask ourselves: What two numbers multiply to -128 and add to 10? Lets find out by listing all of the possible factors of -128


Factors:

1,2,4,8,16,32,64,128,

-1,-2,-4,-8,-16,-32,-64,-128, List the negative factors as well. This will allow us to find all possible combinations

These factors pair up to multiply to -128.

(-1)*(128)=-128

(-2)*(64)=-128

(-4)*(32)=-128

(-8)*(16)=-128

Now which of these pairs add to 10? Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to 10

||||||||
First Number|Second Number|Sum
1|-128|1+(-128)=-127
2|-64|2+(-64)=-62
4|-32|4+(-32)=-28
8|-16|8+(-16)=-8
-1|128|(-1)+128=127
-2|64|(-2)+64=62
-4|32|(-4)+32=28
-8|16|(-8)+16=8


None of these factors add to 10. So the quadratic x%5E2%2B10%2Ax-128 cannot be factored.




So you must use the quadratic formula


So let's use the quadratic formula to solve x%5E2%2B10x-128=0


For more help with the quadratic formula, check out this quadratic formula solver.

Solved by pluggable solver: Quadratic Formula
Let's use the quadratic formula to solve for x:


Starting with the general quadratic


ax%5E2%2Bbx%2Bc=0


the general solution using the quadratic equation is:


x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29




So lets solve x%5E2%2B10%2Ax-128=0 ( notice a=1, b=10, and c=-128)





x+=+%28-10+%2B-+sqrt%28+%2810%29%5E2-4%2A1%2A-128+%29%29%2F%282%2A1%29 Plug in a=1, b=10, and c=-128




x+=+%28-10+%2B-+sqrt%28+100-4%2A1%2A-128+%29%29%2F%282%2A1%29 Square 10 to get 100




x+=+%28-10+%2B-+sqrt%28+100%2B512+%29%29%2F%282%2A1%29 Multiply -4%2A-128%2A1 to get 512




x+=+%28-10+%2B-+sqrt%28+612+%29%29%2F%282%2A1%29 Combine like terms in the radicand (everything under the square root)




x+=+%28-10+%2B-+6%2Asqrt%2817%29%29%2F%282%2A1%29 Simplify the square root (note: If you need help with simplifying the square root, check out this solver)




x+=+%28-10+%2B-+6%2Asqrt%2817%29%29%2F2 Multiply 2 and 1 to get 2


So now the expression breaks down into two parts


x+=+%28-10+%2B+6%2Asqrt%2817%29%29%2F2 or x+=+%28-10+-+6%2Asqrt%2817%29%29%2F2



Now break up the fraction



x=-10%2F2%2B6%2Asqrt%2817%29%2F2 or x=-10%2F2-6%2Asqrt%2817%29%2F2



Simplify



x=-5%2B3%2Asqrt%2817%29 or x=-5-3%2Asqrt%2817%29



So the solutions are:

x=-5%2B3%2Asqrt%2817%29 or x=-5-3%2Asqrt%2817%29




Quadratic_Equations/274322: The roots of the equation 2x squared-10x+8=0 represent the dimension of the rectangle. what is the area of the rectangle
1 solutions

Answer 200221 by jim_thompson5910(28536) About Me  on 2010-02-25 18:15:46 (Show Source):
You can put this solution on YOUR website!
For more help, check out this quadratic formula solver.

Solved by pluggable solver: Quadratic Formula
Let's use the quadratic formula to solve for x:


Starting with the general quadratic


ax%5E2%2Bbx%2Bc=0


the general solution using the quadratic equation is:


x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29




So lets solve 2%2Ax%5E2-10%2Ax%2B8=0 ( notice a=2, b=-10, and c=8)





x+=+%28--10+%2B-+sqrt%28+%28-10%29%5E2-4%2A2%2A8+%29%29%2F%282%2A2%29 Plug in a=2, b=-10, and c=8




x+=+%2810+%2B-+sqrt%28+%28-10%29%5E2-4%2A2%2A8+%29%29%2F%282%2A2%29 Negate -10 to get 10




x+=+%2810+%2B-+sqrt%28+100-4%2A2%2A8+%29%29%2F%282%2A2%29 Square -10 to get 100 (note: remember when you square -10, you must square the negative as well. This is because %28-10%29%5E2=-10%2A-10=100.)




x+=+%2810+%2B-+sqrt%28+100%2B-64+%29%29%2F%282%2A2%29 Multiply -4%2A8%2A2 to get -64




x+=+%2810+%2B-+sqrt%28+36+%29%29%2F%282%2A2%29 Combine like terms in the radicand (everything under the square root)




x+=+%2810+%2B-+6%29%2F%282%2A2%29 Simplify the square root (note: If you need help with simplifying the square root, check out this solver)




x+=+%2810+%2B-+6%29%2F4 Multiply 2 and 2 to get 4


So now the expression breaks down into two parts


x+=+%2810+%2B+6%29%2F4 or x+=+%2810+-+6%29%2F4


Lets look at the first part:


x=%2810+%2B+6%29%2F4


x=16%2F4 Add the terms in the numerator

x=4 Divide


So one answer is

x=4




Now lets look at the second part:


x=%2810+-+6%29%2F4


x=4%2F4 Subtract the terms in the numerator

x=1 Divide


So another answer is

x=1


So our solutions are:

x=4 or x=1





Since the roots are x=1 or x=4, this means that the length is 4 units and the width is 1 unit. So the area is simply A=4*1=4 square units.


expressions/274325: I need help on try to figure out how to evaluate an expression 48 over 2x + 4
1 solutions

Answer 200219 by jim_thompson5910(28536) About Me  on 2010-02-25 18:13:39 (Show Source):
You can put this solution on YOUR website!
Unless you've been given a value of x, you can only simplify: 48%2F%282x%2B4%29=48%2F%282%28x%2B2%29%29=24%2F%28x%2B2%29. So 48%2F%282x%2B4%29=24%2F%28x%2B2%29 where x%3C%3E-2.


Polynomials-and-rational-expressions/274297: Hi. I'm trying to solve 2xy+5x-2y-5 over 3xy+4x-3y-4. Thank you!
1 solutions

Answer 200197 by jim_thompson5910(28536) About Me  on 2010-02-25 17:13:49 (Show Source):
You can put this solution on YOUR website!
The key to this problem is factoring


Let's factor 2xy%2B5x-2y-5


2xy%2B5x-2y-5 Start with the given expression.


%282xy%2B5x%29%2B%28-2y-5%29 Group the terms.


x%282y%2B5%29%2B%28-2y-5%29 Factor out the GCF 'x' from the first group.


x%282y%2B5%29-%282y%2B5%29 Factor out the GCF -1 from the second group.


%28x-1%29%282y%2B5%29 Factor out the GCF 3y%2B4 from the entire expression.


So 2xy%2B5x-2y-5 factors to %28x-1%29%282y%2B5%29

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

Now let's factor 3xy%2B4x-3y-4


3xy%2B4x-3y-4 Start with the given expression.


%283xy%2B4x%29%2B%28-3y-4%29 Group the terms.


x%283y%2B4%29%2B%28-3y-4%29 Factor out the GCF 'x' from the first group.


x%283y%2B4%29-%283y%2B4%29 Factor out the GCF -1 from the second group.


%28x-1%29%283y%2B4%29 Factor out the GCF 3y%2B4 from the entire expression.


So 3xy%2B4x-3y-4 factors to %28x-1%29%283y%2B4%29

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


Now that we have the factorizations, we can now simplify:


%282xy%2B5x-2y-5%29%2F%283xy%2B4x-3y-4%29 Start with the given expression.


%28%28x-1%29%282y%2B5%29%29%2F%283xy%2B4x-3y-4%29 Factor the numerator (see the first factorization above)


%28%28x-1%29%282y%2B5%29%29%2F%28%28x-1%29%283y%2B4%29%29 Factor the denominator (see the second factorization above)


%28highlight%28%28x-1%29%29%282y%2B5%29%29%2F%28highlight%28%28x-1%29%29%283y%2B4%29%29 Highlight the common terms.


%28cross%28%28x-1%29%29%282y%2B5%29%29%2F%28cross%28%28x-1%29%29%283y%2B4%29%29 Cancel out the common terms.


%282y%2B5%29%2F%283y%2B4%29 Simplify.


So %282xy%2B5x-2y-5%29%2F%283xy%2B4x-3y-4%29 simplifies to %282y%2B5%29%2F%283y%2B4%29


In other words, %282xy%2B5x-2y-5%29%2F%283xy%2B4x-3y-4%29=%282y%2B5%29%2F%283y%2B4%29


Note: One thing to point out is that the value of 'x' does not affect the final outcome of the expression since the 'x' terms cancel out. This isn't so obvious when you look at the original expression, but it becomes clear when we reach the last step.


Polynomials-and-rational-expressions/274285: please help solve this problem
11/2x + 4/7x
I know first you find the LCD which is 14x but i don't know what you do after this
11/2x *14 + 4/7x *14
1 solutions

Answer 200188 by jim_thompson5910(28536) About Me  on 2010-02-25 16:50:40 (Show Source):
You can put this solution on YOUR website!
11%2F%282x%29+%2B+4%2F%287x%29 Start with the given expression.


%2811%2A7%29%2F%282x%2A7%29+%2B+4%2F%287x%29 Multiply both the numerator and denominator of the first fraction by 7 (to get the denominator equal to the LCD)


%2811%2A7%29%2F%282x%2A7%29+%2B+%284%2A2%29%2F%287x%2A2%29 Multiply both the numerator and denominator of the second fraction by 2 (to get the denominator equal to the LCD)


77%2F%2814x%29+%2B+8%2F%2814x%29 Multiply.


%2877%2B8%29%2F%2814x%29 Combine the fractions (this is now possible since the denominators are now equal).


85%2F%2814x%29 Add


So 11%2F%282x%29+%2B+4%2F%287x%29=85%2F%2814x%29 where x%3C%3E0


Linear-equations/273991: If a line with equation 3x -ky= 4 has a slope 5/6, find the value of k?
Help?
1 solutions

Answer 200033 by jim_thompson5910(28536) About Me  on 2010-02-24 21:50:45 (Show Source):
You can put this solution on YOUR website!
Solve for 'y' to get y=%283%2Fk%29x-4%2Fk. Notice that the slope is 3%2Fk. Because the given slope is 5%2F6, this means that 3%2Fk=5%2F6. Cross multiply to get 18=5k. Finally, solve for k to get k=18%2F5


Linear-equations/273995: Put the equation 2x - 3y = 15 into slope-intercept form. Think you get two answers...right
1 solutions

Answer 200032 by jim_thompson5910(28536) About Me  on 2010-02-24 21:48:07 (Show Source):
You can put this solution on YOUR website!

2x-3y=15 Start with the given equation.


-3y=15-2x Subtract 2x from both sides.


-3y=-2x%2B15 Rearrange the terms.


y=%28-2x%2B15%29%2F%28-3%29 Divide both sides by -3 to isolate y.


y=%28%28-2%29%2F%28-3%29%29x%2B%2815%29%2F%28-3%29 Break up the fraction.


y=%282%2F3%29x-5 Reduce.


So the equation y=%282%2F3%29x-5 is now in slope intercept form y=mx%2Bb where the slope is m=2%2F3 and the y-intercept is b=-5 note: the y-intercept is the point


Functions/273994: Evaluate f(x)= 4x^2 - 2 for f(1/2)
1 solutions

Answer 200031 by jim_thompson5910(28536) About Me  on 2010-02-24 21:47:27 (Show Source):
You can put this solution on YOUR website!
f%28x%29=4x%5E2-2 Start with the given equation.


f%281%2F2%29=4%281%2F2%29%5E2-2 Plug in x=1%2F2.


f%281%2F2%29=4%281%2F4%29-2 Square 1%2F2 to get 1%2F4.


f%281%2F2%29=1-2 Multiply 4 and 1%2F4 to get 1.


f%281%2F2%29=-1 Combine like terms.


Exponents/273983: My daughter is very confused by this problem: Is there any difference between
-(3)(squared) and -3 (squared)?
1 solutions

Answer 200028 by jim_thompson5910(28536) About Me  on 2010-02-24 21:40:33 (Show Source):
You can put this solution on YOUR website!
If you're talking about -%283%29%5E2 and -3%5E2, then the answer is no. There is no difference between -%283%29%5E2 and -3%5E2 since -%283%29%5E2=-%289%29=-9 and -3%5E2=-9


However, if you're talking about %28-3%29%5E2 and -3%5E2, then there is a difference since %28-3%29%5E2=%28-3%29%2A%28-3%29=9 and -3%5E2=-9


Functions/273851: I am completely stumped on this question.
Given (f+g)(x)=10-3x and (f-g)(x)=5x-14, find f(x) and g(x).
Thanks so much.
1 solutions

Answer 200001 by jim_thompson5910(28536) About Me  on 2010-02-24 17:52:33 (Show Source):
You can put this solution on YOUR website!
Since %28f%2Bg%29%28x%29=10-3x, this means that f%28x%29%2Bg%28x%29=10-3x. Solve for 'f(x)' to get f%28x%29=10-3x-g%28x%29


Also, because %28f-g%29%28x%29=5x-14, we know that f%28x%29-g%28x%29=5x-14


Now plug f%28x%29=10-3x-g%28x%29 into f%28x%29-g%28x%29=5x-14 to get 10-3x-g%28x%29-g%28x%29=5x-14


Combine like terms to get 10-3x-2g%28x%29=5x-14


From here, simply solve for 'g(x)' (think of g(x) as any other variable). Once you have g(x), use that to find f(x).


Rational-functions/273823: Given that +f%28x%29=3x%5E2-7x%2B1+
find f(-1)
find f(x+1)
find f(x+h)
I have spent a lot of time on these problems, and I must be missing something because I cannot get them right.
My answer for the second one was +3x%5E2-7x%2B11+
for the third one was +3x%5E2%2B3h%5E2-7x%2B1+
My answer for the first was the most confusing of all, depending on whether I entered it entirely into my calculator, and if I broke the problem into segments ( +3%28-1%29%5E2-7%28-1%29%2B1+ vs 3-7%2B1 my answer changed. The first was 11, the second was -3.
1 solutions

Answer 199993 by jim_thompson5910(28536) About Me  on 2010-02-24 17:18:08 (Show Source):
You can put this solution on YOUR website!
# 1



f%28x%29=3x%5E2-7x%2B1 Start with the given equation.


f%28-1%29=3%28-1%29%5E2-7%28-1%29%2B1 Plug in x=-1.


f%28-1%29=3%281%29-7%28-1%29%2B1 Square -1 to get 1.


f%28-1%29=3-7%28-1%29%2B1 Multiply 3 and 1 to get 3.


f%28-1%29=3%2B7%2B1 Multiply -7 and -1 to get 7.


f%28-1%29=11 Combine like terms.


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

# 2

f%28x%29=3x%5E2-7x%2B1 Start with the given equation.


f%28x%2B1%29=3%28x%2B1%29%5E2-7%28x%2B1%29%2B1 Replace each 'x' with 'x+1'.


f%28x%2B1%29=3%28x%5E2%2B2x%2B1%29-7%28x%2B1%29%2B1 FOIL


f%28x%2B1%29=3x%5E2%2B6x%2B3-7x-7%2B1 Distribute


f%28x%2B1%29=3x%5E2-x-3 Combine like terms.


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

# 3

f%28x%29=3x%5E2-7x%2B1 Start with the given equation.


f%28x%2Bh%29=3%28x%2Bh%29%5E2-7%28x%2Bh%29%2B1 Replace each 'x' with 'x+h'.


f%28x%2Bh%29=3%28x%5E2%2B2xh%2Bh%5E2%29-7%28x%2Bh%29%2B1 FOIL


f%28x%2Bh%29=3x%5E2%2B6xh%2B3h%5E2-7x-7h%2B1 Distribute


Quadratic_Equations/273826: 4x^2-15x+9=0
1 solutions

Answer 199992 by jim_thompson5910(28536) About Me  on 2010-02-24 17:12:14 (Show Source):
You can put this solution on YOUR website!
For more help, check out this quadratic formula solver.

Solved by pluggable solver: Quadratic Formula
Let's use the quadratic formula to solve for x:


Starting with the general quadratic


ax%5E2%2Bbx%2Bc=0


the general solution using the quadratic equation is:


x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29




So lets solve 4%2Ax%5E2-15%2Ax%2B9=0 ( notice a=4, b=-15, and c=9)





x+=+%28--15+%2B-+sqrt%28+%28-15%29%5E2-4%2A4%2A9+%29%29%2F%282%2A4%29 Plug in a=4, b=-15, and c=9




x+=+%2815+%2B-+sqrt%28+%28-15%29%5E2-4%2A4%2A9+%29%29%2F%282%2A4%29 Negate -15 to get 15




x+=+%2815+%2B-+sqrt%28+225-4%2A4%2A9+%29%29%2F%282%2A4%29 Square -15 to get 225 (note: remember when you square -15, you must square the negative as well. This is because %28-15%29%5E2=-15%2A-15=225.)




x+=+%2815+%2B-+sqrt%28+225%2B-144+%29%29%2F%282%2A4%29 Multiply -4%2A9%2A4 to get -144




x+=+%2815+%2B-+sqrt%28+81+%29%29%2F%282%2A4%29 Combine like terms in the radicand (everything under the square root)




x+=+%2815+%2B-+9%29%2F%282%2A4%29 Simplify the square root (note: If you need help with simplifying the square root, check out this solver)




x+=+%2815+%2B-+9%29%2F8 Multiply 2 and 4 to get 8


So now the expression breaks down into two parts


x+=+%2815+%2B+9%29%2F8 or x+=+%2815+-+9%29%2F8


Lets look at the first part:


x=%2815+%2B+9%29%2F8


x=24%2F8 Add the terms in the numerator

x=3 Divide


So one answer is

x=3




Now lets look at the second part:


x=%2815+-+9%29%2F8


x=6%2F8 Subtract the terms in the numerator

x=3%2F4 Divide


So another answer is

x=3%2F4


Quadratic_Equations/273827: 5x^2-32x-21=0
1 solutions

Answer 199991 by jim_thompson5910(28536) About Me  on 2010-02-24 17:10:59 (Show Source):
You can put this solution on YOUR website!
For more help, check out this quadratic formula solver.

Solved by pluggable solver: Quadratic Formula
Let's use the quadratic formula to solve for x:


Starting with the general quadratic


ax%5E2%2Bbx%2Bc=0


the general solution using the quadratic equation is:


x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29




So lets solve 5%2Ax%5E2-32%2Ax-21=0 ( notice a=5, b=-32, and c=-21)





x+=+%28--32+%2B-+sqrt%28+%28-32%29%5E2-4%2A5%2A-21+%29%29%2F%282%2A5%29 Plug in a=5, b=-32, and c=-21




x+=+%2832+%2B-+sqrt%28+%28-32%29%5E2-4%2A5%2A-21+%29%29%2F%282%2A5%29 Negate -32 to get 32




x+=+%2832+%2B-+sqrt%28+1024-4%2A5%2A-21+%29%29%2F%282%2A5%29 Square -32 to get 1024 (note: remember when you square -32, you must square the negative as well. This is because %28-32%29%5E2=-32%2A-32=1024.)




x+=+%2832+%2B-+sqrt%28+1024%2B420+%29%29%2F%282%2A5%29 Multiply -4%2A-21%2A5 to get 420




x+=+%2832+%2B-+sqrt%28+1444+%29%29%2F%282%2A5%29 Combine like terms in the radicand (everything under the square root)




x+=+%2832+%2B-+38%29%2F%282%2A5%29 Simplify the square root (note: If you need help with simplifying the square root, check out this solver)




x+=+%2832+%2B-+38%29%2F10 Multiply 2 and 5 to get 10


So now the expression breaks down into two parts


x+=+%2832+%2B+38%29%2F10 or x+=+%2832+-+38%29%2F10


Lets look at the first part:


x=%2832+%2B+38%29%2F10


x=70%2F10 Add the terms in the numerator

x=7 Divide


So one answer is

x=7




Now lets look at the second part:


x=%2832+-+38%29%2F10


x=-6%2F10 Subtract the terms in the numerator

x=-3%2F5 Divide


So another answer is

x=-3%2F5


So our solutions are:

x=7 or x=-3%2F5