我们知道,函数y=f(x)若存在反函数,则y=f(x)与它的反函数y=f~(-1)(x)有如下性质：若y=f~(-1)(x)是函数y=f(x)的反函数,则有f(a)=b(?)f~(-1)(b)=a．这一性质的几何解释是y=f(x)与其反函数y=f~(-1)(x)的图像关于直线y=x对称．也就是说若原函数过点(a,b),则其反函数必过点(b,a)．反函数中这个重要的小结论,别看它貌 We know that if there is an inverse function for the function y=f(x), y=f(x) and its inverse function y=f~(-1)(x) have the following properties: if y=f~(-1) (x) is an inverse function of the function y=f(x), then there is f(a)=b(?)f~(-1)(b)=a. The geometrical interpretation of this property is that the image of y=f(x) and its inverse function y=f~(-1)(x) is symmetric about the straight line y=x. In other words, if the original function passes the point (a, b), its inverse function must pass the point (b, a). In this important small conclusion of the inverse function, don’t look at it.