Functional: f(x^2+y)+f(f(x)-y)=2f(f(x))+2y^2
Source: Czech-Polish-Slovak 2001 Q5
April 30, 2013
functionlimitalgebra unsolvedalgebra
Problem Statement
Find all functions that satisfy
f(x^2 + y) + f(f(x) - y) = 2f(f(x)) + 2y^2 \text{ for all }x, y \in \mathbb{R}.