Question 55
Determine all functions $f : \mathbb{R} \to \mathbb{R}$ such that for all real numbers $x$ and $y$ holds
$$
f(x^2 + f(y)) = (f(x) + y^2)^2.
$$
$$
f(x^2 + f(y)) = (f(x) + y^2)^2.
$$
MathNet 2012 Question 55
Math Olympiad Vault · MathNet 2012