Question

what is the solution of the system x+y=0 y=2x+6

Answer 1

Okay, do you know how to do substitution?

Answer 2

no

Answer 3

well, if you take x+y=0, and express y in terms of,

x + y =0
y = -x

So then for both equations to have the same solution set, both equations must share the same coordinates.

Therefore, for the second equation

y = 2x + 6, plug in y = -x into y = 2x + 6 and solve for x.

Then once you found x, plug it into any of the two equations and solve for y.