设函数f{x}=log2x-logx4{0<x<1}.数列{An}的通项An满足f{2的an次方}=2n

问题描述:

设函数f{x}=log2x-logx4{0<x<1}.数列{An}的通项An满足f{2的an次方}=2n
求数列{An}的通项公式.

f{2的an次方}=log2*(2的an次方)-log2的an次方4,{0<x<1}=an-2/an=2n
an^2-2an*n-2=0,an^2-2an*n+n^2=2+n^2,an=(2+n^2)^1/2-n,或是an=-(2+n^2)^1/2-n,因为0怎么由,an^2-2an*n+n^2=2+n^2,得到的an=(2+n^2)^1/2-n,或是an=-(2+n^2)^1/2-n,把它看成是一元二次方程,把n看成常数解AN