已知等比数列{an}满足an＞0,n=1,2等,且a5*a(2n-5)=2^2n,则当n≥1时log2a1+log2a3

来源：学生作业帮编辑：神马作文网作业帮分类：数学作业时间：2024/11/18 03:59:59

已知等比数列{an}满足an＞0,n=1,2等,且a5*a(2n-5)=2^2n,则当n≥1时log2a1+log2a3+..+log2a(2n-1)=
且a5*a(2n-5)=2^2n,n≥3

$已知等比数列{an}满足an＞0,n=1,2等,且a5*a(2n-5)=2^2n,则当n≥1时log2a1+log2a3$

当 n = 3,a5 * a1 = 2^6
即 a1^2 q^4 = 2^6－－－－（1）
当 n = 4 ,a5 * a3 = 2^8
即 a1^2 * q^6 = 2^8－－－－（2）
解得 q = 2,q = -2（因为an＞0,舍去）
a1 = 2,a3 = 2^3,a5 = 2^5.a(2n-1) = 2^(2n-1)
log2 a1 + log2 a3 +..+ log2 a(2n-1)
=log2 2 + log2 2^3 +..+ log2 2^(2n-1)
=1 + 3 +.+ (2n-1)
=[ 1 + (2n-1) ] * n / 2
=n^2

已知等比数列｛an｝为递增数列,且a5²=a10,2[an+a(n+2)]=5a(n+1),则数列｛an｝的通已知等比数列{an}中满足an大于0,n为正整数且a5*a2n-5=2的2n次方则n大于等于1时,loga1+loga2 已知数列an中满足a1=1且当n.=2时,2an*a*(n-1)+an-a(n-1)=0,求通项公式an 已知数列{an}满足a0=1,an=a0+a1+a2+...+a(n-1) (n≥2且n属于N*),则当n属于N*时an 已知数列an是首项a1=32,公比q=1/2的等比数列,数列bn满足bn=1/n(log2a1+log2a2+…+log 已知数列{an}满足a1=1/5,且当n>1,n∈N*时,有a(n-1)/an=2a(n-1)+1/1-2an,设bn= 已知数列{An}满足A1=1/5,且当n>1,n∈N*时,有a(n-1)/an=2a(n-1)+1/1-2an 已知数列an满足a1=1,an+1={2n ,n为奇数 an+2 ,n为偶数 ,且a1+a3+a5+……+a2k- 已知数列{an}满足anan-1=an-1+(-1)n次方(n≥2),且a1=1,则a5/a3= 设等比数列{an}的前n项和为Sn,已知a1=2011,且an+2an+1+an+2=0(N∈N*),则S2012? 已知数列{an}满足a1=1,a(n+1)=3an+2(n属于N) 1.求证数列{an+1}是等比数列 2.求{an}的通项公式为an=an^2+n的数列,若满足a1＜a2＜a3＜a4＜a5,且an＞a(n+1)对n≥8恒成立,则实数a的取