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drk answered: 1901 problems
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Answer 189886 by drk(1908) on 2010-01-18 14:05:47 (Show Source):
You can put this solution on YOUR website!Let x and Y be the numbers. From the given information, we get
(i) 
(ii) 
step 1 - solve for X in (i) to get
(iii) 
step 2 - substitute (iii) into (ii) to get
(iv) 
expand (iv) to get
(v) 
set = 0 to get
(vi) 
divide by -1 and factor to get
(vii) 
solve to get
Y = 2, Y = -8. We have two answers in x,y form as
(-8,2) and (2,-8)
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Equations/258036: How would you write this in standard form using integers? y=2/3x-25/3. Thanks so much! 1 solutions
Answer 189884 by drk(1908) on 2010-01-18 13:59:25 (Show Source):
You can put this solution on YOUR website!We are given
(i) 
standard form requires two things
(1) no fractions
(2) x and y on the same side
--
step 1 - multiply (i) by 3 to get
(ii) 
step 2 - subtract 2x to get

at this point some teacher require positive x's, sop we could write
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Linear-equations/258033: slope and the vertical and horizontal intercept
y=5x+2 can you show me the work so i know how to do this please thank you very much. 1 solutions
Answer 189883 by drk(1908) on 2010-01-18 13:57:01 (Show Source):
You can put this solution on YOUR website!We start with
(i) 
This is similar to
(ii) 
matching up the 2 we get
slope = m = 5.
--
If we were to graph this, it would be a line.
vertical intercept = do you mean x-intercept?
horizontal intercept = do you mean y-intercept?
--
X-intercept is when y = 0. If y = 0, then

--
Y-intercept is when x = 0. If x = 0, then
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Linear_Equations_And_Systems_Word_Problems/258029: Janet invested $27,000, part at 15% and part at 9%. If the total interest at the end of the year is $3,390, how much did she invest at 15%? 1 solutions
Answer 189879 by drk(1908) on 2010-01-18 13:51:31 (Show Source):
You can put this solution on YOUR website!This question is modeled after the I = prt question. IN this case however, we have two investments. So we can write
I = prt + prt
based on the given information, we get
(i) 
simplifying (i) , we get
(ii) 
and then
(iii) 
subtracting, we get
(iv) 
and dividing, we get
x = $11,777.78 @ 15%
and
27000 - x = $15,222.22 @ 9%.
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Rectangles/257815: The length of a rectangle is 2 ft more than four times the width. Express as an interger the maximum width of the rectangle when the perimeter is less than 34 ft ? 1 solutions
Answer 189707 by drk(1908) on 2010-01-17 19:21:44 (Show Source):
You can put this solution on YOUR website!Let length = L and width = W.
from the given information, we get
L = 4W + 2
P = 2L + 2W
34 > 2(4W+2) + 2W
34 > 10W + 4
30 > 10W
3 > W
The maximum width is 2.
If W = 2
L = 10
P = 24 < 34
--
If W = 3
L = 14
P = 34 this is NOT LESS than 34.
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Miscellaneous_Word_Problems/257783: Ricardo wants to replace the wooden door on his flat. The wooden door will be shaped like a rectangular solid and will measure 76 2/3 inches long and 44 1/4 inches wide; and will be 1 3/8 inch thick. How many cubic inches of wood will be needed for the door? Give solution exactly as a mixed number.
1 solutions
Answer 189704 by drk(1908) on 2010-01-17 19:17:30 (Show Source):
You can put this solution on YOUR website!I would suggest turning all fractions into improper then multiply.
76 and 2/3 = 230/3
44 and 1/4 = 177/4
1 and 3/8 = 11/8
--

reduced becomes

which is
4664 + 11/16 cubic inches
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Equations/257811: I'm trying to figure out the answer for 3m+4=19-2n
I tried 3m+4-4=19-2n-4
3m=15-2n
?
I get confused on these, thanks for your help 1 solutions
Answer 189703 by drk(1908) on 2010-01-17 19:05:28 (Show Source):
You can put this solution on YOUR website!Here is the original question
(i) 
I notice you have two variables here. ALso M is next to the n on the keyboard, so it could be one variable. We have four options. Hopefully one of these will answer your question.
--
option 1 - solve (i) for m

subtract 4 from both sides to get

divide by 3 to get

--
option 2 - solve (i) for n

subtract 19 from both sides to get

divide by -2 to get

--
option 3 - m=n solve (i) for m

subtract 4 from both sides to get

add 2m to both sides to get

divide by 5 to get

--
option 4 - m=n solve (i) for n

subtract 4 from both sides to get

add 2n to both sides to get

divide by 5 to get
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Mixture_Word_Problems/257812: A mixture of acid and water is 35% acid. if the mixture contains a total of 40 Liters, how many liters of pure acid are in the mixture? How many liters of pure water are in the mixture? 1 solutions
Answer 189700 by drk(1908) on 2010-01-17 18:58:01 (Show Source):
You can put this solution on YOUR website!This is a mixture problem. Be careful here, as pure acid = 100% acid and water = 0% acid. As a matter of fact any time they give you water it is automatically 0 in the % column. WE have the following table based on given information:
liquid . . . . . . . . . .% . . . . . . . . . . .L . . . . . . . . .%xL
acid . . . . . .. . . . . 100 . . . . . . . . . x . . . . . . . . .100x
water . . . . .. . . . . 0 . . . . . . . . . .. 40-x . . . .. . . . 0
mix . . . . .. . . . . . 35 . . . . . . . . . .40 . . . . . .. .. . 1400
From the third column, we get
100x = 1400
x = 14.
So we have
14 Liters of pure acid
26 liters of pure water
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Matrices-and-determiminant/257807: Use the row echelon method to solve the system of three equations in three unknowns.
x - y + 2z = -2
5x + z = 0
x + 2y+z = 4 1 solutions
Answer 189697 by drk(1908) on 2010-01-17 18:48:38 (Show Source):
You can put this solution on YOUR website!We are given the following:
x - y + 2z = -2
5x + z = 0
x + 2y+z = 4
--
in row echelon form, we have:
1 . . . . . (-1) . . . . . . .2 . . . . . . .(-2)
5 . . . . . .0 . . . . . . . .1 . . . . . . .0
1 . . . . . . 2 . . . . . . . 1 . . . . . .. 4
We need to get a diagonal matrix so take row 2 - 5 row 1 -> row 2; row 3 - row 1 -> row 3
--
1 . . . . . (-1) . . . . . . .2 . . . . . . .(-2)
0 . . . .. . 5 . . . . . . . .(-9) . . .. . . 10
0 . . . .. . 3 . . . . . .. . . -1 . . . . . . . 6
(1/5) row 2 -> row 2
--
1 . . . . . (-1) . . . . . . .2 . . . . . . .(-2)
0 . . . . . . 1 . . . . . . . .(-9/5) . . 2
0 . . . . . . 1 . . . . . . . .3 . . . . . . . 6
row 1 + row 2 -> row 1; row 3 - row 2 -> row 3
--
1 . . . . . . 0. . . . . . . .(1/5) . . . . 0
0 . . . . . . 1 . . . . . . . .(-9/5) . . . 2
0 . . . . . . 0 . . . . . . . .(22/5) . . . .0
(5/24) row 3 -> row 3
--
1 . . . . . . 0. . . . . . . .(1/5) . . . . 0
0 . . . . . . 1 . . . . . . . .(-9/5) . . . 2
0 . . . . . . 0 . . . . . . . .1 . . . . . . . 0
So,
z = 0
y = 2
x = 0
{0, 2, 0}
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Travel_Word_Problems/257809: The distance from Melbourne to London is 10,500 miles. If a jet averages 500 mph between the two cities, What is its travel time in hours? 1 solutions
Answer 189690 by drk(1908) on 2010-01-17 18:30:53 (Show Source):
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Triangles/257796: Find the area of the triangle ABC having vertices A(7,-4) B(3,1) C(-10,-8) 1 solutions
Answer 189687 by drk(1908) on 2010-01-17 18:29:12 (Show Source):
You can put this solution on YOUR website!If you graph these out, you may notice that there are no right angles. This means we can use one of three formulas:
(1) Hero's formula - approximate
To use this we need the 3 distances. They are: sqrt(255), sqrt(61), sqrt(261)
The semi perimeter, s, is about 12.79
A = sqrt(s*(s-a)(s-b)(s-c))
A = 50.5
(2) matrices
Lets use matricies. If we apply matrices, we get 50.5
--
(3) 1/2absinC
This requires trig calculations, which I don't know you have seen.
--
So the area is 50.5.
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Inverses/257805: Inverse of y=4x-2
y=2x+4
y=1/4x + 1/2
y= 1/4x-1/2
y=4x +1/2 1 solutions
Answer 189675 by drk(1908) on 2010-01-17 18:10:36 (Show Source):
You can put this solution on YOUR website!We stat with

step 1 - reverse the x and y to get

step 2 - solve for the new y to get

separating our common denominator, we get

So, the answer is y= 1/4x-1/2
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Matrices-and-determiminant/257803: A company makes 3 types of cable. Cable A requires 3 black wires, 3 white wires, and 2 red wires. Cable B requires 1 black, 2 white, and 1 red. Cable C requires 2 black, 1 white, and 2 red. If 95 black wires, 100 white wires, and 80 red wires were used, then how many of each cable were made? 1 solutions
Answer 189673 by drk(1908) on 2010-01-17 18:05:29 (Show Source):
You can put this solution on YOUR website!Here we have a 3x3 system.
Let the cables be A, B, and C.
(i) 3A + 1B + 2C = 95
(ii) 3A + 2B + 1C = 100
(iii) 2A + 1B + 2C = 80
--
Lets eliminate the B's. Take (ii) - 2*(i) to get
(iv) -3A -3C = -90
lets eliminate the B's. take (ii) - 2*(iii) to get
(v) -1A -3C = -60
--
To eliminate C's, take (v) - (iv) to get
(vi) 2A = 30 so
A = 15 cables
C = 15 cables
B = 20 cables
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Graphs/257802: find the intercerpts and then use them to graph the equation 3y - 9 = 3x 1 solutions
Answer 189672 by drk(1908) on 2010-01-17 17:59:02 (Show Source):
You can put this solution on YOUR website!The x-intercept is when we let y = 0, and solve for x. We get
(i) 
x = -3
The y-intercept is when we let x = 0, and solve for y. We get:
(ii) 
y = 3
Now, we can graph these and create a line.
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Money_Word_Problems/257799: You want to have a $90,000 college fund in 11 years. How much will you have to deposit now under the scenario below. Assume that you make no deposits into the account after the initial deposit.
An APR of 5% compounded daily. 1 solutions
Answer 189671 by drk(1908) on 2010-01-17 17:56:24 (Show Source):
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Trigonometry-basics/257759: How to solve this problem and the steps w/five key points?
y = Sin 4x? I'm a beginner can u help? 1 solutions
Answer 189653 by drk(1908) on 2010-01-17 17:00:22 (Show Source):
You can put this solution on YOUR website!This you really can't solve. You can simplify or graph.
(i) 
--
Now 4x = 2x + 2x, so we get
(ii) 
we have an identity:
sin(A+B) = sinA cosB + sinB cosA
or in our case
(iii) 
But these are the same, so we can write
(Iv) 
--
Now 2x = x + x, so we get
(v) 
we have an identity:
sin(A+B) = sinA cosB + sinB cosA
or in our case
(vi) 
But these are the same, so we can write
(vii) 
From (iv) and (vii), we get
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Polynomials-and-rational-expressions/257734: (x-1)(x^2+10x+24=0...This one has me baffled..I can work 2nd set of parentheses but the (x-1) has got me confused.Is this a valid solvable problem? 1 solutions
Answer 189646 by drk(1908) on 2010-01-17 16:53:22 (Show Source):
You can put this solution on YOUR website!Here is the original question:

step 1 - factor the second polynomial to get

step 2 - set each pat = 0 and solve:
x-1 = 0
x = 1
x + 4 = 0
x = -4
x + 6 = 0
x = -6
we have three answers
{-6, -4, 1}
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Graphs/257736: Lorena borrowed $100 from her father and plans to pay him back at a rate of $10 per week. The graph shows the amount Lorena owes her father. Find the equation that represents this relationship.
A. y= 10x - 100
B. y= 10x - 90
C. y= 100 - 10x
D. y= -100 - 10x 1 solutions
Answer 189600 by drk(1908) on 2010-01-17 15:10:44 (Show Source):
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Graphs/257733: in direct variation if y varies directly with x:
find the equation for the direct variation if y=20 when x= 3 find x when y=8 1 solutions
Answer 189598 by drk(1908) on 2010-01-17 15:09:38 (Show Source):
You can put this solution on YOUR website!Step 1 write y = kx and find k using known x and y information.
y = kx
20 = 3k
k = 20/3
step 2 - rewrite the equation with your new K value as
y = (20/3)x
step 3 find x when y = 8
8 = (20/3)x
24/20 = x
x = 6/5
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Word_Problems_With_Coins/257726: How many ways can you make $0.25 using pennies, nickels, dimes, and quarters
1 solutions
Answer 189597 by drk(1908) on 2010-01-17 15:07:39 (Show Source):
You can put this solution on YOUR website!There appear to be 13 ways. Here they are in {p,n,d,q} form:
{p,n,d,q}
{0,0,0,1}
(0,1,2,0}
{5,0,2,0}
{0,3,1,0}
{5,2,1,0}
{10,1,1,0}
{15,0,1,0}
{0,5,0,0}
{5,4,0,0}
{10,3,0,0}
{15,2,0,0}
{20,1,0,0}
{25,0,0,0}
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