MathDB
Functional equation

Source: Swiss Math Olympiad 2010 - final round, problem 6

March 16, 2010
functionalgebra proposedalgebra

Problem Statement

Find all functions f:RR f: \mathbb{R}\mapsto\mathbb{R} such that for all x x, y y R \in\mathbb{R}, f(f(x))\plus{}f(f(y))\equal{}2y\plus{}f(x\minus{}y) holds.