Problem

Source: Chinese TST 2005

Tags: Gauss, function, induction, search, inequalities unsolved, inequalities



Let $n$ be a positive integer, and $x$ be a positive real number. Prove that $$\sum_{k=1}^{n} \left( x \left[\frac{k}{x}\right] - (x+1)\left[\frac{k}{x+1}\right]\right) \leq n,$$where $[x]$ denotes the largest integer not exceeding $x$.