Question

1.Stiind ca : x+y=13 si z=15 calculati xz+zy .
2.Stiind ca : x-y=12 si z=10 calculati xz+yz.
3.Stiind ca: ab+ac=420 si b+c=14 aflati a.
4.Stiind ca : ab+ac=135 si a=9 ,aflati b-c.
5.Stiind ca :ab+ac+a=165 si b+c =10 ,aflati a.
6.Stiind ca : a+2b+c=51 si 2a+b+2c=42,aflati a+b+c.
7.Daca a,b,c sunt nr. naturale si a+b+c=18 ,iar 2a +b+2c,atunci calculati: (a+c) • (3a+2b+3c).
Ajutorr!!!

Answer 1

Z(X+Y)=15x13=195
z(x+y)=10x12=120
a(b+c)=a.14=420=420:14=30