问题
填空题
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log2012X1+log2012X2+…+log2012X2011的值为______.
答案
由题意可得P(1,1)
对函数f(x)=xn+1求导可得,f′(x)=(n+1)xn
∴y=f(x)在点P处的切线斜率K=f′(1)=n+1,切线方程为y-1=(n+1)(x-1)
令y=0可得,xn=n n+1
∴x1x2…x2011=
•1 2
•2 3
…3 4
=2011 2012 1 2012
∴log2012x1+log2012x2+…+log2012x2011=log2012(x1x2…xn)
=log2012
=-11 2012
故答案为:-1