Respostas

2014-01-29T00:40:17-02:00
Olá 
 métado da substituição :
2x+y=-3
y=-3-2x
x=3-1y/2
 
  6.3-y+3y=-18
-6y+3y=-36
-6y=-18/-6
 y=3

2x+y=-3
2x+3=-3
2x=-6
 x=-6/2
 x=-3

 
 
1 5 1
2014-01-29T10:14:00-02:00
2x+y=-3            y=-3-2x
x-3y=-26

x-3.(-3-2x)=-26
x+9+6x=-26
x+6x=26-9
7x=17
x=17/7

2x+y=-3
2.17/7+y=-3
34/7+y=-3
y=-3-34/7
y=-21/7-34/7
y=-55/7