MathDB
f( - f (x) - f (y))= 1 -x - y , in Zxz

Source: 2020 Dutch IMO TST 3.3

November 22, 2020
functional equationfunctional equation in Zfunctionalalgebra

Problem Statement

Find all functions f:ZZf: Z \to Z that satisfy f(f(x)f(y))=1xyf(-f (x) - f (y))= 1 -x - y for all x,yZx, y \in Z