f(x)=(x-1)(x-2)(x-3).(x-99)(x-100)求f(1)的导数
问题描述：
f(x)=(x-1)(x-2)(x-3).(x-99)(x-100)求f(1)的导数
答
f′(x)=(x-1)′［(x-2)(x-3)(x-4)……(x-100)］+(x-1)［(x-2)(x-3)(x-4)……(x-100)］′ f(x=1)=1×［(-1)(-2)(-3)……(-99)］+(1-1)［(x-2)(x-3)(x-4)……(x-100)］′ =-99!