The product rule is a process of differentiation for a product of two functions. This rule is for differentiating functions where one function is multiplied by another. The rule follows from the limit definition of derivative and is given by:
dy/dx = f ' (x) . g(x) + f(x) . g ' (x)
In this document, the rule is given formally and several examples are worked out.
The document should serve as a useful guide for introductory examples for derivatives.
Knowledge about power rule and derivatives of some trigonometric functions is assumed.