MathDB
(x^2 + y^2)f(xy) = f(x)f(y)f(x^2 + y^2)

Source: Dutch BxMO/EGMO TST 2015 p5

August 24, 2019
algebrafunctional equation

Problem Statement

Find all functions f:R→Rf : R \to R satisfying (x2+y2)f(xy)=f(x)f(y)f(x2+y2)(x^2 + y^2)f(xy) = f(x)f(y)f(x^2 + y^2) for all real numbers xx and yy.