Question

resolva; x+y=1
2x+y=0

Answer 1

x + y = 1
2x + y = 0

y = 1 - x
y = - 2x

1 - x = - 2x
- x + 2x = - 1
x = - 1

y = - 2x
y = - 2 * (- 1)
y = 2