Question

Determinati numerele x,y si z direct proportionale cu 3,4 si 5 , stiind ca 3z-2x-y=35

Answer 1

x / 3 = y / 4 = z / 5 = k                    x = 3k               y = 4k          z =5k
3·5k -2·3k - 4k = 35                         x =21                y= 28           z = 35 
15k  -  6k  -4 k= 35 
5k =35   ; k = 35:5 =7

Answer 2

$\frac{x}{3}= \frac{y}{4}= \frac{z}{5}=K \\ \frac{x}{3}=K \\ x=3K \\ \frac{y}{4}=K \\ y=4K \\ \frac{z}{5}=K \\ z=5K \\ Inlocuim:3*5K-2*3K-4K=35 \\ 15K-6K-4K=35 \\ 5K=35 \\ K=35:5 \\ K=\boxed{7}$
$x=3*7=\boxed{21} \\ y=4*7=\boxed{28} \\ z=5*7=\boxed{35}$