Abstract
In Chapter 3 of the Analyse, l’Hôpital turns his attention to problems of maxima and minima. In a manner analogous to the modern method of finding critical numbers of a function, l’Hôpital solves these problems by finding values of the abscissa x for which either dy = 0 or dy is infinite. Among the problems that l’Hôpital considers is finding the maximum ordinate on the closed loop of the Folium of Descartes, maximizing or minimizing surface area of solids, and the so-called Pulley Problem.