Question

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

Answer 1

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 = $\frac{5-2y}{3}$

$\frac{5-2y}{3}$-y = -10

$\frac{5-5y}{3}$ = -10

5-5y = -30

1-y = -6

y = 7

x = $\frac{5-2*7}{3} = \frac{-9}{3} =$-3

3.

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

5x+7y = 9

5x = 9-7y

x = $\frac{9-7y}{5}$

3*$\frac{9-7y}{5}$+2y = 1

$\frac{27-11y}{5}$ = 1

27-11y = 5

-11y = -22

y = 2

x = $\frac{9-7*2}{5} = \frac{-5}{5}$ = -1