Question 79
Find all functions $f : \mathbb{Q} \to \mathbb{Q}$ such that
$$
f(x + 3f(y)) = f(x) + f(y) + 2y,
$$
for all $x, y \in \mathbb{Q}$.
$$
f(x + 3f(y)) = f(x) + f(y) + 2y,
$$
for all $x, y \in \mathbb{Q}$.
MathNet 2014 Question 79
Math Olympiad Vault · MathNet 2014