[ThE-dArK-lOrD]

May I proposed problem $17)$
Find all $f:\mathbb{R} \rightarrow \mathbb{R}$ such that
$f(y+f(x))^2=f(y)^2+f(8xy)+8x^2f(x^2)$ for all $x,y \in \mathbb{R}$

P.S. Yeah, the answer is $f(x)=0$ for all $x\in \mathbb{R}$ but this is not very easy.