设Sn是等差数列(An)的前n项和,若S3/S6=1/3,求S6/S12=?
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/18 23:44:11
![设Sn是等差数列(An)的前n项和,若S3/S6=1/3,求S6/S12=?](/uploads/image/z/2427907-67-7.jpg?t=%E8%AE%BESn%E6%98%AF%E7%AD%89%E5%B7%AE%E6%95%B0%E5%88%97%28An%29%E7%9A%84%E5%89%8Dn%E9%A1%B9%E5%92%8C%2C%E8%8B%A5S3%2FS6%3D1%2F3%2C%E6%B1%82S6%2FS12%3D%3F)
xA@EhR cH(3 0 ucb4\uex#0^@WLUTi煾;gau|ͪ[-OJ m$($G1z8K%I@4j05l0zbci:ZԪphj 2}9'6Ar=$kh|$]SB$K%o5ט
设Sn是等差数列(An)的前n项和,若S3/S6=1/3,求S6/S12=?
设Sn是等差数列(An)的前n项和,若S3/S6=1/3,求S6/S12=?
设Sn是等差数列(An)的前n项和,若S3/S6=1/3,求S6/S12=?
S3=(a1+a3)*3/2=(2a1+2d)*3/2=3a1+3d
S6=(a1+a6)*6/2=(2a1+5d)*3=6a1+15d
S3/S6=1/3
6a1+15d=9a1+9d
a1=2d
S6=6a1+15d=27d
S12=(a1+a12)*12/2=(2a1+11d)*6=90d
S6/S12=27/90=3/10
设Sn为等差数列{An}的前n项和,求证:{Sn/n}是等差数列
设Sn是等差数列{an}的前n项和,求证:若正整数m,n,p成等差数列,则Sm/m,Sn/n,Sp/p也成等差数列.
设Sn为等差数列an的前n项和.求证Sn/n为等差数列
设等差数列{an}的前n项和为Sn 若a1=Sn>
设等比数列an的公比为q,前n项和为sn,若s(n+1),sn,s(n+2)成等差数列,求q的值
设等比数列[an]的公比为q,前n项和为Sn,若S(n+1),Sn,S(n+2)成等差数列,则q的值?
设等比数列 {an} 的公比为q,前n项和为Sn,若S(n+1),Sn,S(n+2)成等差数列,则q=
设Sn是等差数列{an}的前n项和,已知S8=108,Sn=630,S(n-8)=234,求n.
设Sn是等差数列{an}的前n项和,已知S8=108,Sn=630,S(n-8)=234,求n.
设数列{an}的前n项和为Sn,若对任意正整数,都有Sn=n(a1+an)/2,证明{an}是等差数列.
若等差数列{an}的前n项和为Sn,且满足Sn/S2n为常数,则称该数列为S数列 若首项为a1的各项为正数的等差数列{an}是S数列,设n+h=2008,(n,h为正数) 求1/Sn+1/Sh的最小值 Sn、Sh分别是数列的前n项和和
1.(1) 设Sn是等差数列{an}的前n项和,若a5:a3=5:9,则S9:S5=_________(2) 设Sn,Tn是等差数列{an}{bn}的前n项和,若Sn:Tn=(2n+1):(n+2),a10:b10=_2.设数列{an}的通项公式为an=2,(n=1);3n-4,(n>=2),求{an}的前n项和S
设Sn是等差数列{an}的前n项和,且S5S8,则a1
设{an}是等差数列前n项和为Sn,若S4>=10,S5
数列{an}满足a(n+1)+an=4n-3,若{an}是等差数列,(1)求{an}的通项公式(2)设Sn是{an}的前n项和,数列{an}满足a(n+1)+an=4n-3,若{an}是等差数列,(1)求{an}的通项公式(2)设Sn是{an}的前n项和,且a1=1,求S(2n+1)
设an是公比为q的等比数列,Sn是它的前n项的和,若S(n+1),Sn,S(n+2)成等差数列,则公比q=
设数列{an}的前n项和为sn,若对于所有的正整数n,都有sn=n(a1+an)/2,证明{an}是等差数列设数列{an}的前n项和为sn,若对于所有的正整数n,都有sn=n(a1+an)/2,证明{an}是等差数列
设等差数列an的前n项和为Sn,若S4>=10,S5