Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In calculus, the quotient rule is a method of finding the derivative of a function that is the quotient of two other functions for which derivatives exist. If the function one wishes to differentiate, f(x), can be written as f(x) = frac{g(x)}{h(x)} and h(x)not=0, then the rule states that the derivative of g(x) / h(x) is f''(x) = frac{g''(x)h(x) - g(x)h''(x)}{[h(x)]^2}.