Question

Решите систему уравнений любым способом:
1) 3х+2у=-2
у+х=-1


2) х-у=5
2х+у=1


3) х+у=5
2х+у=1


4) х+у=3
2х+3у=3


5) 2х-у=8
х-у=5

Answer 1

1) 3х+2у=-2
у+х=-1

3x+2y=-2
x=-1-y

3(-1-y)+2y=-2
x=-1-y

-3-3y+2y=-2
x=-1-y

-3y+2y=3-2
x=-1-y

-y=1
x=-1-y

y=1
x=-1-(-1)

y=1
x=0

2) х-у=5
2х+у=1

x=5+y
2х+у=1

x=5+y
2(5+y)+y=1

x=5+y
10+2y+y=1

x=5+y
2y+y=1-10

x=5+y
3y=-9

x=5+y
y=-9/3

x=5+y
y=-3

x=5+(-3)
y=-3

x=2
y=-3