Question 94
Determine all functions $f$ defined on the set of rationals that take rational values for which
$$
f(2 f(x)+f(y))=2 x+y
$$
for each $x$ and $y$.
$$
f(2 f(x)+f(y))=2 x+y
$$
for each $x$ and $y$.
MathNet 2008-part-01 — 165 problems (EN–VI) Question 94
Math Olympiad Vault · MathNet 2008-part-01 — 165 problems (EN–VI)