Question

Resolva os sistemas
2x-y = 0
x-y = 3

Answer 1

{2x-y=0
{x-y=3
x=3+y
2(3+y)-y=0
6+2y-y=0
2y-y=0-6
y=-6
x=3+y
x=3+(-6)
x=3-6
x=-3
S={(-3, -6)}

Answer 2

2x-y =0        |      x-y=3
2(3+y)-y=0  |      x=3+y
6+2y-y=0    |      x=3+(-6)         
y=0-6          |      x=3-6       
 y=-6                  x=-3