一、培养学生集合的思想　　集合思想是最基本的数学思想 ,通过教学 ,使学生认识到 :函数的图象是所有符合条件的组成点的集合 ,让他们更好地运用集合思想理解函数的图象。　　 [例 1]画出函数 ｙ =ｘ2 - 2ｘ - 3的图象　　解 :①列表ｘ - 2 - 10 12 34ｙ 5 0 - 3- 4- 30 5　　 First, the idea of ​​cultivating students’ collections of thoughts is the most basic mathematical thought. Through teaching, students are made to realize that the image of a function is a set of all the constituent points that meet the conditions, so that they can better use the diagram of the set of ideological understanding functions. Like. [Example 1] Draw an image of function y =x2 - 2x - 3 Solution :1 List x - 2 - 10 12 34y 5 0 - 3- 4- 30 5