Question 1
Find all functions $f: \mathbb{R} \mapsto \mathbb{R}$ such that, for all real numbers $x$ and $y$,
$$
f\left(x^{2}+x+f(y)\right)=y+f(x)+f(x)^{2}
$$
$$
f\left(x^{2}+x+f(y)\right)=y+f(x)+f(x)^{2}
$$
MathNet 2019-part-03 — 184 problems (EN–VI) Question 1
Math Olympiad Vault · MathNet 2019-part-03 — 184 problems (EN–VI)