f(f(x - y)) = f(x)f(y) - f(x) + f(y) - xy
Source: VietNamMO 2005,problem4
March 11, 2005
functionalgebra proposedalgebra
Problem Statement
Find all function satisfying the condition:
f(f(x \minus{} y)) \equal{} f(x)\cdot f(y) \minus{} f(x) \plus{} f(y) \minus{} xy