Question

Determinati nr x, y, z a caror suma este.42 stiind ca x si y sunt direct proportionale cu 7 si 2 , iar y si z sunt invers proportionale cu 3 si respectiv 4

Answer 1

x+y+z=42
x/7=y/2  ⇒ x=7y/2
3y=4z  ⇒ z=3y/4
7y/2+y+3y/4=42
14y+4y+3y=168
21y=168
y=8
x=7x8/2=28
z=3x8/4=6