Which statement best describes how to determine whether f(x) 9 and 4x2 is an odd function?

It is difficult to tell what function you have in the question because the browser used by this site is hopelessly inadequate for mathematical notation.

However,

f(x) is an odd function of x if and only if f(-x) = -f(x) for all x.

Common examples are f(x) = x^k where k is any odd integer, f(x) = sin(x).