Răspuns:
b) -x=4-y
5x+2y=8
x=-4+y
5x+2y=8
5(-4+y)+2y=8
-20+5y+2y=8
7y=28
y=4
-x+4=4
-x=0
x=0
c)-3x+4y=-6
y=4-2x
-3x+4(4-2x)=-6
-3x+16-8x=-6
-11x=-6-16=-22
11x=22
x=2
4+y=4
y=0
d) 2x-3y=-3
y=12-3x
2x-3(12-3x)=-3
2x-36+9x=-3
11x=-3+36=33
11x=33
x=3
9+y=12
y=3