ANTIDERIVATIVES: RULES, FORMULAS, ETC. Definition: An antiderivative of a function f(x) is a function F(x) for which F0(x) = f(x). Note: The Mean Value Theorem states that all antiderivatives of a given function differ at most by a constant. Thus if F is an antiderivative of f, any antiderivative of f must be of the form F(x)+C, where C is a ...