一个函数的图像究竟是否存在自公切线,通过极值点不一定能够得到正确的判断。因此回归问题本质,通过定义解题,同时结合函数图象的特征,才能准确判断一个函数是否有自公切线,这往往也是问题解决的捷径。 Whether the image of a function exists from the common tangential line or not, it is not always possible to get the correct judgment through the extreme points. Therefore, by returning to the essence of the problem, we can determine exactly whether a function has self-equality by defining the problem solving and combining the features of the function image. This is often also a shortcut for problem solving.