MathDB
Math Prize 2013 Problem 17

Source:

September 10, 2013
functiontrigonometryalgebradomain

Problem Statement

Let ff be the function defined by f(x)=2sin(πx)f(x) = -2 \sin(\pi x). How many values of xx such that 2x2-2 \le x \le 2 satisfy the equation f(f(f(x)))=f(x)f(f(f(x))) = f(x)?