Question 92
Determine all functions $f:\mathbb R\to\mathbb R$ such that for all real numbers $x,y$,
$$f(f(x)+y)=f(x^2-y)+4yf(x).$$
$$f(f(x)+y)=f(x^2-y)+4yf(x).$$
MathNet 2000 — Math Olympiad Vault Question 92
Math Olympiad Vault · MathNet 2000 — Math Olympiad Vault