(2x+5y)/(x+y)=4,5
2x+5y=4,5x+4,5y
5y-4,5y=4,5x-2x
0,5y=2,5x
y=5x
⇒
y/x=5 deci x/y=1/5 asta e prima cerinta
daca x/y=1/5.......pentru a afla 5x/2y................inmultim in ambele parti cu 5/2 si rezulta
5/2*x/y=5/2*1/5
5x/2y=5/10 asta e cerinta 2..................
in ceea ce priveste cerinta3.....................e vorba oare de (x²+y²)/y²???
y=5x deci (x²+25x²)/25x²⇒26x²/25x²⇒
(x²+y²)/y²=26/25
