Question

Решите систему уравнений:
2х-у=0
3х+11у=75

3х+5у=4
2х-3у=9

Answer 1

1) {2x-y=0|×11
{3x+11y=75

{22x-11y=0
{3x+11y=75

22x-11y+3x+11y=0+75
25x=75|÷25

x=3

2x-y=0
y=2x
y=2×3

y=6

Ответ: (3;6).


2) {3х+5у=4|×2
{2х-3у=9|×(-3)


{6х+10у=8
{-6х+9y=-27

6x+10y+(-6x)+9y=8+(-27)
19y=-19|÷19

y=-1

2x-3y=9
2x=9+3y
2x=9+3×(-1)
2x=9-3
2x=6|÷2

x=3

Ответ: (3;-1).