观点1函数y-f(x)与其反函数y=f-1(x)的图像若有公共点,则公共点必在直线y-x上;观点2若函数y=f(x)有反函数,则它一定是单调函数;观点3函数y=f(x)存在反函数y=f-1(x),则必有f[f-1(x)]=f-1[f(x)]=x成立; If the image of point 1 function yf(x) and its inverse function y=f-1(x) has a common point, the common point must be on line yx; point 2 If the function y=f(x) has an inverse function, then it Must be a monotonic function; the viewpoint 3 function y=f(x) has the inverse function y=f-1(x), then there must be f[f-1(x)]=f-1[f(x)]=x Established;