# Chain rule

### From Conservapedia

This article/section deals with mathematical concepts appropriate for a student in late high school or early university. |

The **chain rule** in calculus is a formula for determining the derivative of a composite function:

The chain rule can also be expressed as:

The chain rule can also be applied to multivariable functions. The derivative of a multivariable function is expressed as follows:

or in vector notation:

where r is the vector function

The function r is sometimes called the *path* of the particle.

Sometimes it might be helpful to change variables into a more convenient form before differentiating.