A cubic function is one in the form .
The "basic" cubic function, , is graphed below.
The function of the coefficient in the general equation is to make the graph "wider" or "skinnier", or to reflect it (if negative):
The constant in the equation is the -intercept of the graph.
The effects of and on the graph are more complicated. However, if you can factor the right side of the equation, you can find one or more -intercepts , and use these to sketch the graph. (Some cubics, however, cannot be factored.)
A cubic function may have one, two or three -intercepts, corresponding to the real roots of the related cubic equation.