MathDB
19th kmo #4

Source: KMO round 2, problem 4

February 3, 2006
functioninductioncalculusderivativealgebrafunctional equationalgebra unsolved

Problem Statement

Find all f:RRf: \mathbb R \to\mathbb R such that for all real numbers xx, f(x)0f(x) \geq 0 and for all real numbers xx and yy, f(x+y)+f(xy)2f(x)2y2=0. f(x+y)+f(x-y)-2f(x)-2y^2=0.