MathDB
Romania District Olympiad 2011 - Grade XI

Source:

March 12, 2011
functionanalytic geometrygraphing linesslopeinequalitiestriangle inequalityreal analysis

Problem Statement

Find all the functions f:[0,1]Rf:[0,1]\rightarrow \mathbb{R} for which we have:
xy2f(x)f(y)xy,|x-y|^2\le |f(x)-f(y)|\le |x-y|,
for all x,y[0,1]x,y\in [0,1].