Question 91
Find all functions $f, f: \mathbb{Q} \to \mathbb{Q}$, such that
$$
f(x + f(y + f(z))) = y + f(x + z)
$$
for all $x, y, z \in \mathbb{Q}$.
$$
f(x + f(y + f(z))) = y + f(x + z)
$$
for all $x, y, z \in \mathbb{Q}$.
MathNet 2012 Question 91
Math Olympiad Vault · MathNet 2012