Question

Stiind ca x/y = 7/9 , rezolvati: 5x+2y
______
2x-y

Answer 1

Salut,

Din x / y = 7 / 9, putem presupune că x = 7k și y = 9k, unde k este un număr real, nenul.

Fracția din enunț devine:

$\dfrac{5\cdot 7k+2\cdot 9k}{2\cdot 7k-9k}=\dfrac{53k}{5k}=\dfrac{53}{5}.$

Simplu, nu ? :-))).

Green eyes.

Answer 2

$\displaystyle \mathtt{\frac{x}{y}=\frac{7}{9}} \\ \\ \mathtt{9x=7y=k} \\ \\ \mathtt{x=\frac{k}{9}} \\ \\ \mathtt{y=\frac{k}{7}} \\ \\ \mathtt{\frac{5x+2y}{2x-y}}= \\ \\ \\ \\ \mathtt{\frac{5\cdot\frac{k}{9}+2\cdot\frac{k}{7}}{2\cdot\frac{k}{9}-\frac{k}{7}}=} \\ \\ \\ \\ \mathtt{\frac{\frac{35k+18k}{63}}{\frac{14k-9k}{63}}=}\\ \\ \\ \\ \mathtt{\frac{63*53k}{63*5k}= \\ \\ \\ \\ \frac{53}{5}}$