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MathNet 2007-part-01 — 187 problems (EN–VI) Question 157

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

Question 157

Suppose $a$, $b$, $c$ are real numbers, with $a + b + c = 3$. Prove that
$$
\frac{1}{5a^2 - 4a + 11} + \frac{1}{5b^2 - 4b + 11} + \frac{1}{5c^2 - 4c + 11} \le \frac{1}{4}.
$$