Respostas

2013-07-03T19:54:15-03:00

a)

x+y= 22

2x-y= 20

*x=22-y

*2(22-y)-y=20

44-2y-y=20

-3y=-24

y=8

*x+8=22

x=14

b)

7x+y=-2

x+5y= -26

*y=-2-7x

*x+5(-2-7x)=-26

x+(-10-35x)=-26

x-10-35x=-26

-34x=-16

x=8/17

*8/17+5y=-26

5y=-26-8/17

5y=-450/17

y=-90/17

 

c)

2x-y= 4

x+2y= -3

*x=-3-2y

2(-3-2y)-y=4

-6-4y-y=4

-6-5y=4

-5y=10

y=-2

*2x-(-2)=4

2x+2=4

2x=6

x=3

1 5 1