Question

Stiind ca x+3*y = 2*y+z=14 calculati :
A) x+5*y+z
B) 3*x+15*y+3*z
C) 5*x + 11*y-2*z
D) 5*x+19*y+2*z
Scrieti tot cum se afla , urgeeent

Answer 1

a) x+3*y =14
     2*y+z=14        le adunam
    ----------------
x+3*y+2*y+z=14+14    ⇒x+5*y+z=28
b) daca inmultim cu 3 obtinem
3*x+15*y+3z =28*3 = 84

c) x+3*y =14    inmultim cu 5
   5*x+15*y=14*5= 70
           2*y+z= 14
    ---------------------------    facem scaderea
   5*x+13*y-2z=56

d) preluam 
5*x+15*y= 70
2*y+z= 14  inmultim cu2 ⇒ 4*y+2z=14*2=28
----------------------------------------------------------------------le adunam
5*x+15*y+4*y+2z=70+28
5*x+19*y+2z=98