同学们有没有尝试着把自己的一些!发现记录下来呢?不妨试一试,也许会有意想不到的收获哟.学习不等式,可以类比方程,好像不太困难.然而,解题时却发现有一类含有待定字母的不等式组比较麻烦.通过老师的讲评,我感觉采用数形结合的方法求解这类问题比较简便.例1若关于x的不等式组(?)只有四个整数解,则a的取值范围是____.一看题目,我不知该从何下手,因为我只会解第一个不等式,解得x<21. Students have not tried to put some of their own! Record it? May wish to try, there may be unexpected gains yo. Learning inequality, analogy, it seems not too difficult. However, the problem was found when there is a class Inequality group containing the letter to be undetermined is too much trouble.Through the teacher’s comment, I feel that it is more convenient to solve this kind of problem by using the method of number and form combination.Example 1 If the group of inequalities (x) has only four integer solutions, then The value range is ____. A look at the title, I do not know where to start, because I will only solve the first inequality, solution x <21.