MathDB
Turkey Junior Olympiad 2000, Part II - P3

Source:

January 18, 2013
algebrapolynomial

Problem Statement

f:RRf:\mathbb{R}\rightarrow \mathbb{R} satisfies the equation f(x)f(y)af(xy)=x+yf(x)f(y)-af(xy)=x+y , for every real numbers x,yx,y. Find all possible real values of aa.