Question

Dacă {x;y}sunt direct proporționale cu {2;5}si x y=42, atunci x =........,y=..........

Answer 1

x=2k
y=5k 
x ori y = 42
2k ori 5k =42
10k=42
k=42:10
k=4,2
x=2 ori 4,2=8,4
y=21 

Answer 2

{X;Y} d.p. {2;5}
x·y=42
$\frac{x}{2} = \frac{y}{5}=K$
x=2K
y=5K
2K·5K=42
10K=42
K=42:10
K=4,2
x=4,2·2=8,4
y=4,2·5=21