Question

Use the substitution method to solve the following system of equations.

9x + y = 0
18x + 4y = –8

Pic for the answer: http://tinypic.com/r/5xqr9u/7

Answer 1

solve for y
so you get -9x=y
plug that equation in
18x + 4(-9x)=-8
-18x=-8
x=4/9
plug that into the first to get y
9(4/9)+y=0
y=-4

Answer 2

Thanks :)

Answer 3

18x+4y=-8
9x+2y=-4
& 9x+y=0 so y=-9x
9x+2y=-4
9x-18x=-4
x=4/9 and hence y=-4