Question

Решите систему уравнений:

х + у = 11,
2х – у = -5.

Answer 1

$left { {{x+y=11} atop {2x-y=-5}} right. \ 1)x + y = 11, x=11-y \ 2)2x-y=-5 \ 2(11-y)-y=-5 \ 22-2y-y=-5 \ -3y=-27 \ y=9 \ 3)x+y=11 \ x+9=11 \ x=2$