MEMO 2010, Problem T-2: Stronger than Cauchy
Source:
September 12, 2010
inequalitiesCauchy Inequalityinequalities proposed
Problem Statement
For each integer , determine the largest real constant such that for all positive real numbers we have
\frac{a_1^2+\ldots+a_n^2}{n}\geqslant\left(\frac{a_1+\ldots+a_n}{n}\right)^2+C_n\cdot(a_1-a_n)^2\mbox{.}(4th Middle European Mathematical Olympiad, Team Competition, Problem 2)