设正整数列{an}为一个等比数列且a2=4,a4=16求lgan+1 +lgan+2 +...+lg2n
设正数数列{an}为一等比数列,且a2=4,a4=16,求lim(lgan+1+lgan+2+...+lga2n)/n^
设a1,a2,a3,.an都是正数,且构成等比数列,求证1/lga1*lga2+1/lga2*lga3+.1/lgan-
已知正项等比数列{an}中,a2×a (n-1)+a4 ×a(n-3)=200,则lga1+lga2+...lgan=?
若数列{an}是公比为q的等比数列,且bn=lgan,求证{bn}为等差数列
已知数列an是等比数列,a1=2,a4=16 设数列bn=lgan 求证bn是等差数列并求其前n项和
在等比数列{an}lgan=3n+5,求an
数列{an}、{bn}分别为正项等比数列,Tn,Rn分别是数列{lgan}{lgbn}的前n项和,且Tn/Rn=n/2n
设{an}为等差数列,且公差d为正数,已知a2+a3+a4=15,又a2,a3-1,a4成等比数列,求a1和d?
设{An}为等差数列,且公差d为正数,已知a2+a3+a4=15,又a2,a3-1,a4成等比数列,求a1和d
已知数列{an}满足:lgan=3n+5,试用定义证明{an}是等比数列 lgan=3n+5
在等比数列an中,已知n为正整数,a1+a2+a3+a4+...+an=2^n-1,求a1^2+a2^2+...+an^
设正数数列{an}是个等比数列 且a2=4 a4=16求lim(n趋向于无穷)(lga(n+1)+lga(n+2)+..