Răspuns:
a.
adunam cele 2 ecuații si ne rezulta: 5x=5=>x=1
x+2y=-1=>2y=-1-1=-2=>y=-1
b.adunam cele 2 ecuatii:4x=-8=>x=-2
x-4y=-14=>-4y=-14+2=-12=>y=3
c.se scad cele 2 ecuatii: 3y=-3=>y=-1
4x+y=-5=>4x=-5+1=-4=>x=-1
d.se scad:9y=27=>y=3
3x=21-5*3=21-15=6=>x=2
