但有的教材并非如此，本文指出了教材中对拐点的不充分定义，并证明了拐点与极值点的不重合。
This paper points out the insufficient definition in some textbooks and also proves non coincidence of the yieding point and extreme point.
极值点和拐点是高阶导数应用中两个常见的概念。
The point of minima value and the point of inflexion are two common concepts of derivative.
应用推荐