Question 99
Determine all functions $f: \mathbb{R} \rightarrow \mathbb{R}$ such that for all real $x, y$, we have
$$
f\left(x^{2}+x y+f\left(y^{2}\right)\right)=x f(y)+f\left(x^{2}\right)+y^{2}
$$
$$
f\left(x^{2}+x y+f\left(y^{2}\right)\right)=x f(y)+f\left(x^{2}\right)+y^{2}
$$