O inegalitate draguta

[Andi Brojbeanu]

Un paralelipiped dreptunghic are dimensiunile \( x, y, z \) si diagonala \( d \). Aratati ca \( \frac{d^4}{ad^4+bx^4}+\frac{d^4}{ad^4+by^4}+\frac{d^4}{ad^4+bz^4}\ge\frac{6\sqrt{a}-\sqrt{b}}{2a\sqrt{a}} \) oricare ar fi \( a>0 \) si \( b\ge 0 \).