Question

Aflati numerele x,y si z stiind ca sunt direct proportionale cu 2 5 si 7 si ca produsul lor este 560

Answer 1

x supra 2=y supra 5=z supra 7 =k .
x=2k.
y=5k.
z=7k.
x*y*z=560.
2k*5k*7k=560.
70k la a treia=560.
k la a treia =560:70=8.
k la a treia =8.
k = 2.
x=2*2=4.
y=5*2=10.
z=7*2=14.

Answer 2

xyz=560

x/2=y/5=z/7

x/2=y/5 => y=5x/2
x/2=z/7 => z=7z/2

x*5x/2*7x/2=560
35x^3/4=560
35x^3=2240
x^3=2240:35
x^3=64
x^3=4^3
=> x=4

=> y=(5*4)/2=20/2=10
z=(7*4)/2=28/2=14