Question

Determinati nr. x,y,z stiind ca sunt direct peoportionale cu 4,5 si respectiv 7,iar suma lor este egala cu 64.

Answer 1

x , y , z dp cu 4 , 5 , 7
x + y + z = 64
$\frac{x}{4}= \frac{y}{5} = \frac{z}{7}=k=> x=4k ; y = 5k;z=7k$
Inlocuim in x+y+z=64 
4k+5k+7k=64 => 16k = 64 / : 16 => k=4
Deci x = 4*4=16
        y = 5*4=20
        z = 7*4=28

Answer 2

(x,y,z) d.p. (4,5,7)
x+y+z=64
x/4=y/5=z/7=K
x=4K
y=5K
z=7K
4K+5K+7K=64
16K=64
K=64:16
K=4
x=4x4⇒x=16
y=4x5⇒y=20
z=4x7⇒z=28
Verificare:16+20+28=64