函数图象是函数的形,堪称学好函数的关键,用图象法表示函数关系,可以从整体上直观形象地研究函数的变化情况.《数学课程标准(实验)》指出:在函数这一章的教学中,要重视图形在数学学习中的作用,挖掘函数图象对函数概念和性质的理解,对数学理解、数学思考的辅助功能.例如在研究方程根的个数和函数零点个数时常常需要借助函数的图象,但是在利用函数图象研究问题 The function image is the shape of the function, which is the key to learning the function. Using the image method to express the function relation, the function can be studied visually from the whole. “Mathematics Course Standard (Experiment)” points out that in the function Chapter teaching, we should pay attention to the role of graphics in mathematics learning, mining functional image understanding of the concept and nature of the function, understanding of mathematics, mathematical thinking of auxiliary functions. For example, the number of roots in the study and the number of zero function It is often necessary to rely on the image of the function, but to study the problem using the function image