The product rule is used whenever we need to differentiate 2 (or more) functions that are multiplied together. For example, we could differentiate the function f(x)=(x+3)(x-3) using the Product Rule. This example can also be differentiated using the basic differentation rules that have been taught in year 11 if we expand the brackets first.

The product rule is very helpful when we start attempting to differentiate more complex functions such as g(x)=(x^5+3x+3)(2x+3)^2 ***

*** Please note that the symbol "^" denotes the power of