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F(xf(x)+f(y))=(f(x))^2+y

Source: Japan Mathematical Olympiad Finals 2004, Problem 2

November 7, 2005
functionalgebra proposedalgebra

Problem Statement

Find all functions f:RRf : \mathbb{R} \mapsto \mathbb{R} such that f(xf(x)+f(y))=(f(x))2+yf(xf(x)+f(y)) =(f(x))^2+y for all  x,yR.\ x,y \in \mathbb{R}.