Question

For the following system, if you isolated x in the second equation to use the substitution method, what expression would you substitute into the first equation?

2x+y=8
-x-3y=-12

Answer 1

x = 12 - 3y

Explanation:

- x - 3y = - 12 ( multiply through by - 1 )

x + 3y = 12 ( subtract 3y from both sides )

x = 12 - 3y

then substitute x = 12 - 3y into the first equation