设Sn是等差数列{an}的前n项和,若S7=35,则a4等于A.8 B.7 C.6 D.5
来源:学生作业帮助网 编辑:六六作业网 时间:2024/12/25 16:33:55
设Sn是等差数列{an}的前n项和,若S7=35,则a4等于A.8B.7C.6D.5设Sn是等差数列{an}的前n项和,若S7=35,则a4等于A.8B.7C.6D.5设Sn是等差数列{an}的前n项
设Sn是等差数列{an}的前n项和,若S7=35,则a4等于A.8 B.7 C.6 D.5
设Sn是等差数列{an}的前n项和,若S7=35,则a4等于
A.8 B.7 C.6 D.5
设Sn是等差数列{an}的前n项和,若S7=35,则a4等于A.8 B.7 C.6 D.5
答案D Sn是等差数列{an}的前n项和,若S7=7a4=35,∴a4=5,选D. 查看原帖>>
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