Three Radicals, At Least Nine

★ 7/10SubstitutionalgebraAM-GMinequality

Problem

Let x,y,zx, y, z be positive reals with xyz=1xyz = 1. Prove that

1+8x+1+8y+1+8z⩾9.\sqrt{1 + 8x} + \sqrt{1 + 8y} + \sqrt{1 + 8z} \geqslant 9.

Answer

Solution

Difficulty7/10
TopicsSubstitution, algebra, AM-GM, inequality

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