Question 4
Determine all functions $f$ from $\mathbb{R}$ to $\mathbb{R}$ such that, for all real $x$ and $y$, we have the equality
$$
f(x+y)=f(x-y)+f(f(1-x y))
$$
$$
f(x+y)=f(x-y)+f(f(1-x y))
$$
MathNet 2016-part-02 — 184 problems (EN–VI) Question 4
Math Olympiad Vault · MathNet 2016-part-02 — 184 problems (EN–VI)