R+ FE with arbitrary constant
Source: APMO 2023/4
July 5, 2023
APMOAPMO 2023functional equationfe
Problem Statement
Let be a given positive real and be the set of all positive reals. Find all functions such that f((c+1)x+f(y))=f(x+2y)+2cx \textrm{for all } x,y \in \mathbb{R}_{>0}.