How do you solve the system of equations 2y = 10-7x2y=107x and 2x=20-2y2x=202y?

1 Answer
Nov 8, 2017

Solve for xx, then yy using elimination.

x = -2, y = 12x=2,y=12

Explanation:

First, move xx and yy to the same side of the equation so they are on top of each other. Make sure to watch your signs. Add 7x7x to the top and add 2y2y to the bottom.

7x + 2y = 107x+2y=10
2x + 2y= 202x+2y=20

Multiply bottom equation by -11 to eliminate yy.

7x + 2y = 107x+2y=10
-2x - 2y = -202x2y=20

Add the bottom equation to the top. You're left with only xx.

5x = -105x=10

Solve for xx, then plug xx into either of the original equations to get yy.

x = -2, y = 12x=2,y=12