How do you solve 3x+4y=-103x+4y=−10 and x-4y=2x−4y=2?

1 Answer
Leslie
Mar 21, 2016

x = -2; y = -1x=−2;y=−1

Explanation:

First solve for xx by adding the two equations:

3x + 4y = -103x+4y=−10
+x - 4y = 2x−4y=2

This gives you:
4x = -84x=−8, so x = -2x=−2

Then you can solve for yy by either plugging -2−2 in for xx or by multiplying the second equation by -3−3 and adding the two equations again:

    #3x + 4y = -10#

+-3(x - 4y) = 2*-3−3(x−4y)=2⋅−3

This gives:
16y = -1616y=−16, so y = -1y=−1

You can verify your answer by plugging -2−2 in for xx and -1−1 in for yy in both equations.

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