考察这样的问题 :已知函数ｙ=ｘ-ａ的图象与其反函数的图象有公共点 ,求实数ａ的取值范围 .避开具体教法不谈 ,樊老师在文 [1 ]中引导学生得到下面一种解法 ,这就是ｙ=ｘ-ａ(ｘ≥ａ)在 [ａ ,+∞ )上是增函数 ,它有反函数因为如果ｙ=ｆ(ｘ)单调增 ,且ｙ =ｆ(ｘ)与ｙ=ｆ- 1 (ｘ) Consider such a problem: Knowing that the image of the function y=x-a has a common point with the image of the inverse function, find the range of the value of the real number a. To avoid the specific teaching method, Fan, in the article [1] The student is guided to the following solution. That is, y=x-a(x≥a) is an increasing function on [a,+∞ ]. It has an inverse function because if y=f(x) increases monotonically, and y = f(x) and y=f- 1 (x)