The sign of the expression inside the square root determines the number of critical points. If it is positive, then there are two critical points, one is a local maximum, and the other is a local minimum. If , then there is only one critical point, which is an inflection point. If , then there are no (real) critical points. In the two latter cases, that is, if is nonpositive, the cubic function is strictly monotonic. See the figure for an example of the case .