In mathematics, a cubic function is a function of the form
where a is nonzero; or in other words, a polynomial of degree three. The derivative of a cubic function is a quadratic function. The integral of a cubic function is a quartic function.
Bipartite cubics
The graph of
where 0 < a < b is called a bipartite cubic. This is from the theory of elliptic curves.
You can graph a bipartite cubic on a graphing device by graphing the function
corresponding to the upper half of the bipartite cubic. It is defined on
Root-finding Formula
The formula for finding the roots of a cubic function is fairly complicated. Therefore, it is common for some students to use the rational roots test or a numerical solution instead.
If we have
Let
and
Now, let
and
The solutions are
See also: cubic equation, spline.