SOLUTION: -4x+7y=-5 x-4y=-1 solve each system by substitution

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Question 840308: -4x+7y=-5
x-4y=-1
solve each system by substitution

Answer by mxgirl22(39) About Me  (Show Source):
You can put this solution on YOUR website!

-4x+7y=-5
x-4y=-1
solve each system by substitution
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1.) Note: I'm going to label each equation.

Equation #1) -4x%2B7y=-5
Equation #2) x-4y=-1

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2.) Get "x" by itself in equation #2


Equation #2)

x-4y=-1
x-4y%2B4y=-1%2B4y
x=-1%2B4y

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3.) Now that we have "x" by itself in equation #2, plug in x=-1+4y into equation #1.

Equation #1)
-4x%2B7y=-5

-4%28-1%2B4y%29%2B7y=-5

4-16y%2B7y=-5

4-9y=-5

4-4-9y=-5-4

-9y=-9

-9y%2F-9=-9%2F-9
y=1

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4.) Next, use the "y" value we found and plug in to either equation #1 or #2 to find "x" value.

Equation #1)

-4x%2B7y=-5
-4x%2B7%281%29=-5
-4x%2B7=-5
-4x%2B7-7=-5-7
-4x=-12

-4x%2F-4=-12%2F-4
x=3

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5.) Check using x=3 & y=1


Equation #2)
x-4y=-1
%283%29-4%281%29=-1
3-4=-1
-1=-1

Checks!
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6.) Answer.

x=3
y=1