MathDB
Inequality

Source: Baltic way 2009

November 11, 2009
inequalitiesalgebrapolynomialinequalities proposed

Problem Statement

Let a1,a2,,a100 a_1,a_{2},\ldots ,a_{100} be nonnegative integers satisfying the inequality a1(a11)(a120)+a2(a21)(a220)++a100(a1001)(a10020)100999879.a_1\cdot (a_1-1)\cdot\ldots\cdot (a_1-20)+a_2\cdot (a_2-1)\cdot\ldots\cdot (a_2-20)+\\ \ldots+a_{100}\cdot (a_{100}-1)\cdot\ldots\cdot (a_{100}-20)\le 100\cdot 99\cdot 98\cdot\ldots\cdot 79. Prove that a1+a2++a1009900a_1+a_2+\ldots+a_{100}\le 9900.