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\sqrt{2a^2+bc}+\sqrt{2b^2+ac}+\sqrt{2c^2+ab} >= 3 \sqrt{ab+bc+ca}

Source: Ukraine TST 2012 p1

April 29, 2020
inequalitiesalgebra

Problem Statement

Let a,b,ca, b, c be positive reals. Prove that 2a2+bc+2b2+ac+2c2+ab3ab+bc+ca\sqrt{2a^2+bc}+\sqrt{2b^2+ac}+\sqrt{2c^2+ab}\ge 3 \sqrt{ab+bc+ca}