解:当x1时fx)连续 y=x y=ux 当x=1时 lim f(x)=lim x=1 x-1 x→1 lim f(x)=lim x=1 x→1 x→1f lim f(x=lim f(x)=f(=1 x→1 x→1 fx)在x=1也连续 则fx)是连续函数解:当x1时f(x)连续 当x=1时 lim ( ) lim 1 2 1 1 = = → − → − f x x x x lim ( ) lim 1 1 1 = = → + → + f x x x x o y x y=x y=x 2 lim ( ) lim ( ) (1) 1 1 1 = = = → − → + f x f x f x x f(x)在x=1也连续 则 f(x)是连续函数