Each week Manhattan GMAT posts a GMAT question on our blog and follows up with the answer the next day. Are you up for the challenge?
For which of the following functions f(x) is the relation f(f(x)) = f(f(f(f(x)))) NOT true for at least some values of x not equal to zero?
(A) f(x) = -|x|
(B) f(x) = 2 – x
(C) f(x) = 3x
(D) f(x) = 4/x
(E) f(x) = 5