Just as the critical points for a function of one variable are found by differentiation, the same techniques can be applied to a multivariable function to determine where it is stationary. We begin with a reminder of critical points for a function of one variable, before looking at partial differentiation of a multivariable function with a worked example.

The 3D plots used in the video are all generated by the Maple Calculator App which you can download for free from Google Play and the App Store.