Editing Derivative test (section)

{{Short description|Method for finding the extrema of a function}}
In [[calculus]], a '''derivative test''' uses the [[derivative]]s of a [[function (mathematics)|function]] to locate the [[Critical point (mathematics)|critical point]]s of a function and determine whether each point is a [[local maximum]], a [[local minimum]], or a [[saddle point]]. Derivative tests can also give information about the [[Concave function|concavity]] of a function.

The usefulness of derivatives to find [[maxima and minima|extrema]] is proved mathematically by [[Fermat's theorem (stationary points)|Fermat's theorem of stationary points]].