Integration Rules and Formulas Integral of a Function A function ϕ(x) is called a primitive or an antiderivative of a function f(x), if ?'(x) = f(x). Let f(x) be a function. Then the collection of all its primitives is called the indefinite integral of f(x) and is denoted by ∫f(x) dx. Thus, where ϕ(x) is primitive of […]