Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In calculus, the reciprocal rule is a shorthand method of finding the derivative of a function that is the reciprocal of a differentiable function, without using the quotient rule or chain rule.It is also possible to derive the reciprocal rule from the chain rule, by a process very much like that of the derivation of the quotient rule. One thinks of frac{1}{g(x)} as being the function frac{1}{x} composed with the function g(x). The result then follows by application of the chain rule.