Question 9
Find all real-valued functions $f$ satisfying
$$
f(2x + f(y)) + f(f(y)) = 4x + 8y
$$
for all real numbers $x$ and $y$.
$$
f(2x + f(y)) + f(f(y)) = 4x + 8y
$$
for all real numbers $x$ and $y$.
MathNet 2026 — Part 06 Question 9
Math Olympiad Vault · MathNet 2026 — Part 06