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mexico inequality

Source: 2nd National Women's Contest of Mexican Mathematics Olympiad 2023 , level 1+2 p7

July 22, 2023
Mexicoalgebrainequalities

Problem Statement

Suppose aa and bb are real numbers such that 0<a<b<10 < a < b < 1. Let
x=1b1b+a,y=1ba1bandz=1ba1b.x= \frac{1}{\sqrt{b}} - \frac{1}{\sqrt{b+a}},\hspace{1cm} y= \frac{1}{b-a} - \frac{1}{b}\hspace{0.5cm}\textrm{and}\hspace{0.5cm} z= \frac{1}{\sqrt{b-a}} - \frac{1}{\sqrt{b}}.
Show that xx, yy, zz are always ordered from smallest to largest in the same way, regardless of the choice of aa and bb. Find this order among xx, yy, zz.