Решение систему методом сложения

1){х — у = 3
{x + y = 5

2){х – у = -10
{2х + Зу = 15

3) {3х + 2y = 1
{2х + 5y = 8
ОЧЕНЬ

1.

x-y+x+y = 3+5

2x = 8

x = 4

4-y = 3

y = 1

2.

x-y+2x+3y = -10+15

3x+2y = 5

3x = 5-2y

x =

-y = -10

= -10

5-5y = -30

1-y = -6

y = 7

x = -3

3.

3x+2y+2x+5y = 1+8

5x+7y = 9

5x = 9-7y

x =

3*+2y = 1

= 1

27-11y = 5

-11y = -22

y = 2

x = = -1