Move the sliders to show the relationships between
the points on the cubic curve with the first and
and second derivatives.

1. When the green slider is moved it shows that at the maximum point
of the cubic curve f ' (x) = 0 and f '' (x) < 0.
2. When the red slider is moved it shows that at the minimum point
of the cubic curve f '(x) = 0 and f ''(x) >0.
3. When the blue slider is moved it shows that at the point of inflection
of the cubic curve f ''(x) = 0.