IMO Shortlist 1995 problem A3
Dodao/la:
arhiva2. travnja 2012. Let
![n](/media/m/a/e/5/ae594d7d1e46f4b979494cf8a815232b.png)
be an integer,
![n \geq 3.](/media/m/9/7/1/9719b4240a94de4632da4d5e360a7adf.png)
Let
![a_1, a_2, \ldots, a_n](/media/m/9/2/c/92c14c25a50ea2e6e7d3f457e8ea9a16.png)
be real numbers such that
![2 \leq a_i \leq 3](/media/m/9/2/e/92e76be4e9a7fc92d89cef559daa9e7b.png)
for
![i = 1, 2, \ldots, n.](/media/m/a/c/4/ac4225c756ac0a7117d1ce43c0c8643d.png)
If
![s = a_1 + a_2 + \ldots + a_n,](/media/m/3/5/2/3522771f83b9bc4bd28fdab9af3a73ab.png)
prove that
%V0
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