Graph of the derivative function
Drag the point x along the x-axis to move the point P along the graph of f(x) and the corresponding point Q along the graph of f '(x). For a particular value of x, try to predict whether the point Q will be above or below the x-axis. Reset the construction by clicking the "reset" button in the upper right corner of the applet.
Barbara D'Ambrosia, Created with GeoGebra