利用求导数的方法研究与函数的极值有关的问题,我们都清楚的一个事实是:使导函数的函数值等于零的自变量x的值未必是极值点的横坐标,前者是后者的必要不充分条件.但是具体到解题过程中,往往因为忽略这个事实而导致问题的求解出现错误.由于错误的隐蔽性较强、不易发现,所以解题时要有一 Using the derivative method to study the problems related to the extremum of the function, we all clearly understand the fact that the value of the argument x that makes the function value of the derivative function equal to zero is not necessarily the abscissa of the extremum point. The former is the latter. Insufficient conditions are necessary. However, in the process of solving a problem, the solution to the problem is often caused by ignoring this fact. Since the error is more concealed and difficult to find, there must be a problem solving.