Question

1) {x+y=-2
{2x-y=-4

2) {x-y=1
{x+3y=9

Answer 1

1) x=-2-y
2x-y=-4
2(-2-y)-y=-4
y=0
x=-2-0
x=-2
(x,y)=(-2,0)

-2+0=-2
2•(-2)-0=-4
-2=-2
-4=-4
(x,y)=(-2,0)