a)2x-y=1
3x-6y+9+2x-2y=5x-5y-3y+9
2x-y=1
5x-8y+9=5x-8y+9
Sistem,incompatibil.
b)6x+15y-2x-4y=4x+4y+7y
2x+4y+4=3x-3y+3-x+7y+1
4x+11y=4x+11y
2x+4y+4=2x+4y+4
Sistem,incompatibil.
c)5x-9y=1
2x-4=3y-3
5x-9y=1
2x-3y=1
Inmultim,a,doua,ecuatie,cu,(-3)
5x-9y=1
-6x+9y=-3
_______
-x//////=-2=>x=2,si,y=1