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Regional Olympiad - FBH 2013 Grade 12 Problem 1

Source: Regional Olympiad - Federation of Bosnia and Herzegovina 2013

September 24, 2018
algebraInequality

Problem Statement

If aa, bb and cc are nonnegative real numbers such that a2+b2+c2=1a^2+b^2+c^2=1, prove that 12a1+a4+b1+b4+c1+c49310\frac{1}{2} \leq \frac{a}{1+a^4}+\frac{b}{1+b^4}+\frac{c}{1+c^4} \leq \frac{9\sqrt{3}}{10}