Номер 1547

Решите систему уравнений способом сложения:

| x-8y-17=0

| 3x+4y-23=0

| 15x+11y-47=0

| 5x-y+17=0

{ x - 8y - 17 = 0

{3x+4y - 23 = 0 |*2

{ x - 8y = 17

{ 6x + 8y = 46

x - 8y + 6x+8y = 17+46

7x = 63

x = 63/7

x = 9

9 - 8y = 17

-8y = 17-9

-8y = 8

y = 8 / (-8)

y = - 1

ответ : (9; - 1)

{15x + 11y - 47 = 0

{ 5x - y + 17 = 0 |*11

{ 15x + 11y = 47

{ 55x - 11y = - 187

15x + 11y + 55x - 11y = 47 + (-187)

70x = - 140

x = - 140/70

x = - 2

15 * (-2) + 11y = 47

-30 + 11y = 47

11y = 47+30

11y=77

y = 77/11

y = 7

ответ : (- 2; 7)