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MathNet 2022-part-02 — 197 problems (EN–VI) Question 69

Math Olympiad Vault · MathNet 2022-part-02 — 197 problems (EN–VI)

Question 69

Let $a$ be a strictly positive real number and $n \geqslant 1$ an integer. Prove that
$$
\frac{a^{n}}{1+a+\ldots+a^{2 n}} \lt \frac{1}{2 n}
$$