MathDB
fuctional in R, f(x)f(y) = f(x + y) + xy

Source: Dutch BxMO TST 2010 p2

August 24, 2019

Problem Statement

Find all functions f:RRf : R \to R satisfying f(x)f(y)=f(x+y)+xyf(x)f(y) = f(x + y) + xy for all x,yRx, y \in R.