初中数学中的函数,是社会生活的提炼,同时也服务于社会生活.但在学习函数自变量的取值范围这部分内容时,有相当一部分同学感到理解难,入门难.其实,当你掌握了它的“性格”以后,就会觉得它不但很容易,还很有趣. The function of junior high school mathematics is the refinement of social life, but also serves the social life. However, when learning the function variable’s range of values, a considerable number of students feel that it is difficult to understand and that it is difficult to get started. In fact, when you master After its “character”, it will feel that it is not only easy, but also very interesting.