Question

Решите систему уравнений 
{x-3y=6{2x+y=5

Answer 1

{x-3y=6
{2x+y=5

1)x-3y=6
x=6+3y
2)2(6+3y)+y=5
12+6y+y=5
7y=-7
y=-1

2)x=6+3*(-10)=6-3=3

Answer 2

{x-3y=6   x(-2) {-2x+6y= -12
{2x+y=5           {2x+y=5
                          7y= -7
                           y= -7:7
                          {y= -1
                          {x-3*(-1)=6
                           x+4=6
                           x=6-4
                           x=2