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how do i solve with substitution for this problem.4x+3y=-8

                                                                          -8x+y=-12

 

 

Thnxlaugh

 Mar 24, 2016
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Solve the following system:
{4 x+3 y = -8
y-8 x = -12

 

In the second equation, look to solve for y:
{4 x+3 y = -8
y-8 x = -12

 

Add 8 x to both sides:
{4 x+3 y = -8
y = 8 x-12

 

Substitute y = 8 x-12 into the first equation:
{4 x+3 (8 x-12) = -8
y = 8 x-12

 

4 x+3 (8 x-12) = (24 x-36)+4 x = 28 x-36:
{28 x-36 = -8
y = 8 x-12

 

In the first equation, look to solve for x:
{28 x-36 = -8
y = 8 x-12

 

Add 36 to both sides:
{28 x = 28
y = 8 x-12

 

Divide both sides by 28:
{x = 1
y = 8 x-12

 

Substitute x = 1 into the second equation:
Answer: |x = 1          and             y=-4

 Mar 24, 2016

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