导数是研究函数的有力工具,在高三学了导数后,许多问题的讨论方便很多．但是在这之前学习函数、解析几何、数列、不等式等内容时还没有导数工具,因此同学们往往习惯于用初等方法来处理相关问题．这样,学习导数时要有意识地用导数来解相关题目,用导数一统天下． Derivatives are powerful tools for the study of functions. After learning the derivatives in the third year, many problems are much easier to discuss. However, there are no derivative tools for learning functions, analytical geometry, sequences, inequalities, etc., so students are often accustomed to dealing with related problems with elementary methods. In this way, when learning the derivative, we must consciously use the derivative to solve the relevant topic, and use derivative to dominate the world.