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Chisinau MO p131 1976 X sum x_i^2 <= - nab if sum x_i=0

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March 16, 2021
algebrainequalities

Problem Statement

The sum of the real numbers x1,x2,...,xnx_1, x_2, ...,x_n belonging to the segment [a,b][a, b] is equal to zero. Prove that x12+x22+...+xn2nab.x_1^2+ x_2^2+ ...+x_n^2 \le - nab.