IMO Shortlist 2018 problem A1
Dodao/la:
arhiva3. listopada 2019. Let $\mathbb{Q}_{>0}$ denote the set of all positive rational numbers. Determine all functions $f:\mathbb{Q}_{>0}\to \mathbb{Q}_{>0}$ satisfying $$f(x^2f(y)^2)=f(x)^2f(y)$$for all $x,y\in\mathbb{Q}_{>0}$
Izvor: https://www.imo-official.org/problems/IMO2018SL.pdf