MathDB
Inequality with absolute value

Source: Romania EGMO TST 2023 Day 2 P4

February 23, 2023
inequalitiesabsolute valueromaniaalgebra

Problem Statement

Let n3n\geqslant 3 be an integer and a1,,ana_1,\ldots,a_n be nonzero real numbers, with sum SS{}. Prove that i=1nSaiain1n2.\sum_{i=1}^n\left|\frac{S-a_i}{a_i}\right|\geqslant\frac{n-1}{n-2}.