题目内容
设曲线y=xn+1(n∈N*)在点(1,1)处的切线与x轴的交点的横坐标为xn,则x1·x2·…·xn等于 ( ).
A.![]() | B.![]() | C.![]() | D.1 |
B
∵f′(x)=(n+1)xn,
∴f′(1)=n+1,
故切线方程为y-1=(n+1)(x-1),
令y=0得切线与x轴交点横坐标xn=
,
∴x1·x2·…·xn=
×
×…×
=![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824034806881414.png)
∴f′(1)=n+1,
故切线方程为y-1=(n+1)(x-1),
令y=0得切线与x轴交点横坐标xn=
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824034806897426.png)
∴x1·x2·…·xn=
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824034806913338.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824034806928382.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824034806897426.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824034806881414.png)
![](http://thumb.zyjl.cn/images/loading.gif)
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