等比数列{an}中,若a1·a6·a11=e,则ln(a4·a8)=
问题描述:
等比数列{an}中,若a1·a6·a11=e,则ln(a4·a8)=
答
a1·a6·a11=e,
(a6)^3=e,
a6=e^1/3
ln(a4·a8)
=ln(a6)^2
=lne^2/3
=2/3