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MathNet 2007-part-01 — 187 problems (EN–VI) Question 43

Math Olympiad Vault · MathNet 2007-part-01 — 187 problems (EN–VI)

Question 43

Let $x$, $y$ and $z$ be positive real numbers such that $\sqrt{x}+\sqrt{y}+\sqrt{z}=1$. Prove that
$$
\frac{x^{2}+y z}{\sqrt{2 x^{2}(y+z)}}+\frac{y^{2}+z x}{\sqrt{2 y^{2}(z+x)}}+\frac{z^{2}+x y}{\sqrt{2 z^{2}(x+y)}} \geq 1
$$