Sixth Problem
Source: Last round of the Bulgarian Mathematical Olympiad 2009 Maybe Hard
June 22, 2009
integrationcalculusderivativeinequalities proposedinequalities
Problem Statement
Prove that if , are arbitrary taken real numbers and
are positive real numbers, than
\left(\sum_{i,j \equal{} 1}^{n}\frac {a_{i}a_{j}}{c_{i} \plus{} c_{j}}\right)\left(\sum_{i,j \equal{} 1}^{n}\frac {b_{i}b_{j}}{c_{i} \plus{} c_{j}}\right)\ge \left(\sum_{i,j \equal{} 1}^{n}\frac {a_{i}b_{j}}{c_{i} \plus{} c_{j}}\right)^{2}.