Question

Kochani, pomóżcie;)

{2x-y=4 -x+y=-7

{5x-4y=80 2x+y=6

{x-y=2 2x+3y=18

Answer 1

1.

2x-y=4

-x+y=-7

 

2x-y=4

y=-7+x

 

2x+7-x=4

y=-7+4

 

x=-3

y=-10

 

2.

5x-4y=80

2x+y=6

 

5x-4y=80

 y=6-2x

 

5x-4(6-2x)=80

y=6-2x

 

5x-24+8x=80

y=6-2x

 

13x=104

y=6-2x

 

x=8

y=-10

 

3.

x-y=2

2x+3y=18

 

x=2+y

2(2+y)+3y=18

 

x=2+y

4+2y+3y=18

 

x=2+y

5y=14

 

x=2+y

y=2,8

 

x=4,8

y=2,8