Question 157
Find all functions $f : \mathbb{Q}^+ \to \mathbb{Q}^+$ such that
$$
f(xf(x) + f(y)) = (f(x))^2 + y
$$
for all positive rationals $x, y$.
$$
f(xf(x) + f(y)) = (f(x))^2 + y
$$
for all positive rationals $x, y$.
MathNet 2017-part-06 — 176 problems (EN–VI) Question 157
Math Olympiad Vault · MathNet 2017-part-06 — 176 problems (EN–VI)