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x+3y=18 -x-4y=-25

 Jan 20, 2016
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Solve the following system:
{x+3 y = 18 |     (equation 1)
-x-4 y = -25 |     (equation 2)
Add equation 1 to equation 2:
{x+3 y = 18 |     (equation 1)
0 x-y = -7 |     (equation 2)
Multiply equation 2 by -1:
{x+3 y = 18 |     (equation 1)
0 x+y = 7 |     (equation 2)
Subtract 3 × (equation 2) from equation 1:
{x+0 y = -3 |     (equation 1)
0 x+y = 7 |     (equation 2)
Collect results:
Answer: | x = -3              and              y=7
 

 Jan 20, 2016

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