要求: P,(o=f(o) f(ro) P(x)=f(x0) P(xo)=f(xo)of xo 0 2021/2/20 62021/2/20 6 要求：( ) ( ) 0 0 P x f x n  =  ( ) ( ) 0 0 P x f x n  =  . . . . . . . . . ( ) ( ) 0 ( ) 0 ( ) P x f x n n n = x y 0 o x y = f (x) ( ) 0 f x • ( ) ( ) 0 0 P x f x n =