MathDB
Turkey TST 2010 Q2

Source:

September 1, 2010
inequalitiesinequalities proposed

Problem Statement

Show that cyc(a2+b2)(a2ab+b2)2423(a2+b2+c2)(1a+b+1b+c+1c+a) \sum_{cyc} \sqrt[4]{\frac{(a^2+b^2)(a^2-ab+b^2)}{2}} \leq \frac{2}{3}(a^2+b^2+c^2)\left(\frac{1}{a+b}+\frac{1}{b+c}+\frac{1}{c+a}\right) for all positive real numbers a,b,c.a, \: b, \: c.