函数是初中数学中一个非常重要而又比较难学的概念．求函数自变量的取值范围是函数题中最基本的题．现举例说明三忡常见类型的解题方法一、已知函数式．求自变量的取植范围初中阶段接触的函数．有整式、分式、根·式表示的函数．以及由它们之间的两个或两个以一L的式予表示的函 Function is a very important and difficult to learn concept in junior high school mathematics. Finding the value range of the function argument is the most basic question in the function question. An example is given to illustrate the common types of problem solving methods. Seek the function of accessing the independent variable in the junior high school. There are functions represented by integers, fractions, and roots. And letters expressed by a pair of L or two between them