Răspunsuri

  • Utilizator Brainly
2014-09-11T16:50:49+03:00
(x+y)+(y-z)=x+2y -z= 17+4=21
x+y-(y-z)=x+y-y+z=x+z=17-4=13
2 1 2
2014-09-11T17:07:48+03:00
X+y=17=> x=17-y
y-z=4=>y=4-z 
daca y=4-z =>x=17-4-z
                     x=13-z

x+2y-z=13-z+2(4-z)-z=13-z+8-2z-z=21-4z
x+z=13-z+z=13
2 4 2