首页 > 留学知识库

问题: 导数问题

F(x)=(x-1)(x-2)(x-3)....(x-100).求F'(99)
(答案为-98)

解答:

F(x)=(x-1)(x-2)(x-3)....(x-100).
=g(x)*(x-99)
g(x) = (x-1)(x-2)..(x-98)(x-100);

F'(x) = f(x)(x-99) + (x-1)(x-2)..(x-98)(x-100)
f(x)是一多项式, f(x) =g'(x);

F'(99) = g(99)
= 98*97*...*1*(-1)
= -98!