2＝lim(x→0) (f(1)－f(1-2x))/(e^x-1) ＝lim(x→0) (f(1)－f(1-2x))/x ＝2×lim(x→0) (f(1-2x)－f(1))/(-2x) ＝2×f'(1) 所以,f'(1)＝1 f(x)以7为周期,所以f(x+7)＝f(x),求导得f'(x+7)＝f'(x) 所以,f'(8)＝f'(1)＝...