IMO Shortlist 1995 problem A3


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2. travnja 2012.
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Let n be an integer, n \geq 3. Let a_1, a_2, \ldots, a_n be real numbers such that 2 \leq a_i \leq 3 for i = 1, 2, \ldots, n. If s = a_1 + a_2 + \ldots + a_n, prove that \frac{a^{2}_{1}+a^{2}_{2}-a^{2}_{3}}{a_{1}+a_{2}-a_{3}}+\frac{a^{2}_{2}+a^{2}_{3}-a^{2}_{4}}{a_{2}+a_{3}-a_{4}}+\ldots+\frac{a^{2}_{n}+a^{2}_{1}-a^{2}_{2}}{a_{n}+a_{1}-a_{2}}\leq 2s-2n.
Izvor: Međunarodna matematička olimpijada, shortlist 1995