Question

x-y=1
x+2y=0
alguém sabe?

Answer 1

x-y=1  
x+2y=0 ->x=-2y

x-y=1
-2y-y=1
-3y=1
y=-1/3

x+2y=0
x+2(-1/3)=0
3x+6(-1)=0
3x-5=0
x=5/3

x=5/3 e y=-1/3