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

To test whether a function is odd, determine whether f(−x) = −f(x). Substituting −x into f gives f(−x) = 9 − 4(−x)², which should be compared with −(9 − 4x²). Therefore, the statement in choice C describes the correct test.

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