MathDB
f(x + 1/x^2) = f(x) + [f(1/x)]^2

Source: IMO Shortlist 1995, A5

August 10, 2008
functionalgebrafunctional equationIMO Shortlist

Problem Statement

Let R \mathbb{R} be the set of real numbers. Does there exist a function f:RR f: \mathbb{R} \mapsto \mathbb{R} which simultaneously satisfies the following three conditions?
(a) There is a positive number M M such that x: \forall x: \minus{} M \leq f(x) \leq M. (b) The value of f(1)f(1) is 11. (c) If x0, x \neq 0, then f \left(x \plus{} \frac {1}{x^2} \right) \equal{} f(x) \plus{} \left[ f \left(\frac {1}{x} \right) \right]^2