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MathNet 2017-part-02 — 176 problems (EN–VI) Question 41

Math Olympiad Vault · MathNet 2017-part-02 — 176 problems (EN–VI)

Question 41

Prove that for all positive real numbers $a$, $b$ and $c$ the following inequality holds
$$
\frac{a}{b+c} + \frac{b}{c+a} + \frac{c}{a+b} + \sqrt{\frac{ab+bc+ca}{a^2+b^2+c^2}} \ge \frac{5}{2}.
$$