已知曲线f(x)=xn+1(n∈N*)与直线x=1交于点P,若设曲线y=f(x)在点P处的切线与x轴交点的横坐标为xn,则log2011x1+log2011x2+…+log2011x2010的值为__

题目简介

已知曲线f(x)=xn+1(n∈N*)与直线x=1交于点P,若设曲线y=f(x)在点P处的切线与x轴交点的横坐标为xn,则log2011x1+log2011x2+…+log2011x2010的值为__

题目详情

已知曲线f(x)=xn+1(n∈N*)与直线x=1交于点P,若设曲线y=f(x)在点P处的切线与x轴交点的横坐标为xn,则log2011x1+log2011x2+…+log2011x2010的值为______.
题型:填空题难度:中档来源:不详

答案

求导函数,可得f′(x)=(n+1)xn,
设过(1,1)的切线斜率k,则k=f′(1)=n+1,
∴切线方程为y-1=(n+1)(x-1)
令y=0,可得xn=class="stub"n
n+1

∴x1•x2…x2010=class="stub"1
2
×class="stub"2
3
×…×class="stub"2010
2011
=class="stub"1
2011

∴log2011x1+log2011x2+…+log2011x2010
=log2011(x1×x2×…×x2010)
=log2011class="stub"1
2011
=-1.
故答案为:-1.

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