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turkey nmo 2006 q4

Source:

January 6, 2007
inequalities unsolvedinequalities

Problem Statement

x1,...,xnx_{1},...,x_{n} are positive reals such that their sum and their squares' sum are equal to tt. Prove that ijxixj(n1)2tt1\sum_{i\neq{j}}\frac{x_{i}}{x_{j}}\ge\frac{(n-1)^{2}\cdot{t}}{t-1}