A Sum of Absolute Lines

Problem

Let nn be a positive integer and xRx \in \mathbb{R}. Prove that

i=1nix12n2+2nn1.\sum_{i=1}^n |ix - 1| \geqslant \sqrt{2n^2 + 2n} - n - 1.

Answer

Solution

Difficulty8/10
TopicsConvexity, Absolute Value, algebra, AM-GM, inequality

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