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National Spain Olympiad 2004, Problem 3

Source: National Spain Olympiad 2004

May 31, 2017
algebraFunctional Equations

Problem Statement

Represent for Z\mathbb {Z} the set of all integers. Find all of the functions f:{f:} ZZ \mathbb{Z} \rightarrow \mathbb{Z} such that for any x,y{x,y} integers, they satisfy: f(x+f(y))=f(x)y.{f(x + f(y)) = f(x) - y.}