With the sliders you can adjust the parameters of the function (for a not equal to 0 it is a cubic function).
What do the points A and B represent?
Make the first derivative f'(x) visible by clicking on the bubble next to it in the Algebra view

Questions

What link is there between the roots of the first derivative and the stationary points (extrema) of f(x)?
What is the point G? Is there a connection between point G and ?
What about the second derivative of f? What does it tell you?