Derivatives and stationary values
Select or input a function to see the first and second derivatives plotted on the same axes as the function.
This applet is useful for exploring the link between functions and their stationary values (minima, maxima and inflection points).
For example, after selecting the function you can see that the first derivative is a straight line; the place where it crosses the x-axis corresponds to a stationary value. The second derivative is constant and negative; this corresponds to a local maximum.