IMO Shortlist 2001 problem A4
Dodao/la:
arhiva2. travnja 2012. Find all functions

, satisfying
for all

.
%V0
Find all functions $f: \mathbb{R} \rightarrow \mathbb{R}$, satisfying
$$f(xy)(f(x) - f(y)) = (x-y)f(x)f(y)$$
for all $x,y$.
Izvor: Međunarodna matematička olimpijada, shortlist 2001