关于盗墓笔记的网名:f(x)=(x-1)(x-2)(x-3).......(x-10) 求f'(9)=?

来源:百度文库 编辑:中科新闻网 时间:2024/04/28 22:04:55
快帮帮我,谢谢了

f'(x)=-10628640 + 25507152x - 25228500 x^2 + 13667720 x^3 -
4510275 x^4 + 946638 x^5 - 127050 x^6 + 10560 x^7 - 495 x^8 + 10 x^9

f'(9)=-40320

f'(x)=[(x-1)(x-2)(x-3).......(x-10)]'
=[(x-1)(x-2)(x-3).......(x-8)(x-10)]'(x-9)
+[(x-1)(x-2)(x-3).......(x-8)(x-10)] (x-9)'
-->代入x=9
f'(9)
=0+(9-1)(9-2)(9-3)……(9-8)(9-10)
= -40320

应用导数乘法法则很容易求解~规律很浅显的
(UV)~=U~V+UV~
(UVW)~=U~VW+UV~W+UVW~
......

说下 楼上的看错题了吧,人家求的是导数

f(9)=(9-1)(9-2)(9-3)……(9-10)
=8*7*6*5*4*3*2*1*0*(-1)
=0

求导后都等于0除了8*7*6*5*4*3*2*1*-1=-40320
所以f'(9)==-40320

=8*7*6*5*4*3*2*1*0*(-1)
=0