olymmath

JBMO-SL 2014 A9

Let nn be a positive integer, and let x1,…,xn,y1,…,ynx_{1}, \ldots, x_{n}, y_{1}, \ldots, y_{n} be positive real numbers such that x1+…+xn=y1+…+yn=1x_{1}+\ldots+x_{n}=y_{1}+\ldots+y_{n}=1. Show that

∣x1−y1∣+…∣xn−yn∣≤2−min⁡1≤i≤nxiyi−min⁡1≤i≤nyixi\left|x_{1}-y_{1}\right|+\ldots\left|x_{n}-y_{n}\right| \leq 2-\min _{1 \leq i \leq n} \frac{x_{i}}{y_{i}}-\min _{1 \leq i \leq n} \frac{y_{i}}{x_{i}}

Dataset text NuminaMath olympiads. Quoted with source.

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