Question

Se considera numerele reale x,y si z.
a) Daca xy+xz=10 si x=2,calculati y+z
b) Daca x-y=4 si z=5,calculati xz-yz
c) Daca xy+yz=20 si y=5,calculati x=z

Answer 1

a) xy+xz=x(y+z)=2(y+z)=10/:2..... → y+z=5........... b) z(x-y)=5*4=xz-yz=20........ c)y(x+z)=5(x+z)=20/:5..... 2x=4/:2........ x=z=2

Answer 2

a) xy +xz= 10

x(y+z)=10

2* (y+z)=10

y+z=5

b)x-y=4

xz- yz= z(x-y)  = 5*4=20

c)xy + yz=20

y( x+z)=20

5(x+z)=20

x+z=4