Răspuns :
c) x+2y=8
x-y =-1=>x=y-1
y-1+2y=8
3y=9
y=3
x=y-1=3-1=2
d)2x-y =9
x+2y =2=>x=2-2y
2(2-2y)-y=9
4-4y-y=9
-5y=5
y=-1
x=2-2y=2-2(-1)=2+2=4
c) x+2y=8
x-y =-1=>x=y-1
y-1+2y=8
3y=9
y=3
x=y-1=3-1=2
d)2x-y =9
x+2y =2=>x=2-2y
2(2-2y)-y=9
4-4y-y=9
-5y=5
y=-1
x=2-2y=2-2(-1)=2+2=4