44-th Polish Mathematical Olympiad 1992/1993
Source:
February 5, 2009
inequalitiesinequalities unsolved
Problem Statement
If are positiv real numbers, prove the inequality :
\frac {xu \plus{} xv \plus{} yu \plus{} yv}{x \plus{} y \plus{} u \plus{} v} \geq \frac {xy}{x \plus{} y} \plus{} \frac {uv}{u \plus{} v}