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MathNet 2019-part-04 — 184 problems (EN–VI) Question 122

Math Olympiad Vault · MathNet 2019-part-04 — 184 problems (EN–VI)

Question 122

Suppose that $x_{1}, x_{2}, x_{3}, \ldots, x_{n}$ are real numbers between $0$ and $1$ with sum $s$. Prove that

$$
\sum_{i = 1}^{n} \frac{x_{i}}{s + 1 - x_{i}} + \prod_{i = 1}^{n}(1 - x_{i}) \leq 1.
$$