Question

решите систему
х-2у=1
2х-у=2
Пожалуйста)

Answer 1

x-2y=1
2x-y=2

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

2(1+2y)-y=2
2+4y-y=2
3y=0
y=0

x=1+2*0=1

Ответ: (1;0) 

Answer 2

$left { {{x=1+2y} atop {2(1+2y)-y=2}} right. left { {{x=1+2y} atop {2+4y-y=2}} right. left { {{x=1+2y} atop {3y=0}} right. left { {{x=1+2y} atop {y=0}} right. left { {{x=1} atop {y=0}} right.$