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MathNet 2015-part-05 — 191 problems (EN–VI) Question 35

Math Olympiad Vault · MathNet 2015-part-05 — 191 problems (EN–VI)

Question 35

Let $n \in \mathbb{N}^*$. Prove that
$$
\frac{a}{(n+1)a+b+c} + \frac{b}{a+(n+1)b+c} + \frac{c}{a+b+(n+1)c} \le \frac{1}{2}\sqrt{\frac{3}{n}},
$$
for every $a, b, c \in (0, \infty)$. Find the cases of equality.