IMO 2020 Shortlist A8
Let R be the set of positive real numbers. Determine all functions f : R Ñ R such that, for all positive real numbers x ...
Category: Algebra
Problem
Let R be the set of positive real numbers. Determine all functions f : R
Ñ Rsuch that, for all positive real numbers x and y, f
x fpxyq ˘ y “ fpxqfpyq ` 1.
(Ukraine) 6 Saint-Petersburg — Russia, 18th–28th September 2020