Respostas

2013-09-23T19:05:10-03:00
-4y=24
-y=24/4
-y=6
y=-6

x-2*(-6)=12
x-(-12)=12
x+12=12
x=12-12
x=0
1 5 1
2013-09-23T19:05:27-03:00
 \left \{ {{x-2y=12} \atop {x+2y=12}} \right.
x-2y=12
x=12+2y
x+2y=12
12+2y+2y=12
2y+2y=12-12
4y=0
y= \frac{0}{4}
y=0
x-2y=12
x-0=12
x=12-0
x=12
S{0,12}
1 5 1