5x + 7y = -9 { -10x - 6y= 2 Solve For The X and Y Coordinate

Answer 1

These used to confuse me, too! What we want is to make either the x or y coefficients to be opposites so they cancel out. If we multiply the 1st equation by 2, we end up with 10x and -10x.

10x + 14y = -18

-10x -6y = 2

If we add the two equations together, 10x + (-10x) = 0, so they cancel out.

8y = -16

y = -2

5x + 7(-2) = -9

5x - 14 = -9

5x = 5

x = 1

(1,-2)