设Sn为等差数列{an}的前n项和,若S3=3,S6=24,则a9多少?还有一题:已知各项均为正数的等比数列{an},a1a2a3=5,a7a8a9=10,则a4a5a6等于多少?
来源:学生作业帮助网 编辑:作业帮 时间:2024/08/26 21:32:18
![设Sn为等差数列{an}的前n项和,若S3=3,S6=24,则a9多少?还有一题:已知各项均为正数的等比数列{an},a1a2a3=5,a7a8a9=10,则a4a5a6等于多少?](/uploads/image/z/2702588-68-8.jpg?t=%E8%AE%BESn%E4%B8%BA%E7%AD%89%E5%B7%AE%E6%95%B0%E5%88%97%7Ban%7D%E7%9A%84%E5%89%8Dn%E9%A1%B9%E5%92%8C%2C%E8%8B%A5S3%3D3%2CS6%3D24%2C%E5%88%99a9%E5%A4%9A%E5%B0%91%3F%E8%BF%98%E6%9C%89%E4%B8%80%E9%A2%98%EF%BC%9A%E5%B7%B2%E7%9F%A5%E5%90%84%E9%A1%B9%E5%9D%87%E4%B8%BA%E6%AD%A3%E6%95%B0%E7%9A%84%E7%AD%89%E6%AF%94%E6%95%B0%E5%88%97%EF%BD%9Ban%EF%BD%9D%2Ca1a2a3%3D5%2Ca7a8a9%3D10%2C%E5%88%99a4a5a6%E7%AD%89%E4%BA%8E%E5%A4%9A%E5%B0%91%3F)
xRN@jk`f:?=5]7 Kc#G*1>pH܀D_S`/x;35n\h{ιmRJt4r؏q ,A}'|Sb9%OPבKˇP9m/ZPg7yT]4zv=
Lp )o=6ӕb-xxđ;]ϾbkL Q
/R~0#DmJ5'µ:%U (?.UUU+̪efv(Owdu%Δ6CRI!
B2gLb,!T|4:ioWD|k D
设Sn为等差数列{an}的前n项和,若S3=3,S6=24,则a9多少?还有一题:已知各项均为正数的等比数列{an},a1a2a3=5,a7a8a9=10,则a4a5a6等于多少?
设Sn为等差数列{an}的前n项和,若S3=3,S6=24,则a9多少?
还有一题:已知各项均为正数的等比数列{an},a1a2a3=5,a7a8a9=10,则a4a5a6等于多少?
设Sn为等差数列{an}的前n项和,若S3=3,S6=24,则a9多少?还有一题:已知各项均为正数的等比数列{an},a1a2a3=5,a7a8a9=10,则a4a5a6等于多少?
设首项为a1,公差为d
s3=a1+a2+a3
=a1+(a1+d)+(a1+2d)
=3a1+3d
s6=s3+a4+a5+a6
=3a1+3d+(a1+3d)+(a1+4d)+(a1+5d)
=6a1+15d
3a1+3d=3
6a1+15d=24
a1=-1,d=2
a9=a1+8d=15
设首项为a1,公比为q
a1a2a3=a1(a1q)(a1q^2)=a1^3q^3
a7a8a9=(a1q^6)(a1q^7)(a1q^8)=a1^3q^21
(a1a2a3)(a7a8a9)=a1^6q^24=5*10=50
a1^3q^12=√50
a4a5a6=(a1q^3)(a1q^4)(a1q^5)=a1^3q^12=√50
设Sn为等差数列an的前n项和.求证Sn/n为等差数列
设Sn为等差数列{An}的前n项和,求证:{Sn/n}是等差数列
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=
设等差数列an的前n项和为Sn,若S4>=10,S5
设等差数列{AN}的前N项和为SN,若S9>0,S10
设等差数列 {an}的前n 项和为Sn,若S9>0 ,S10
在等差数列{an},设Sn为它的前n项和,若S15>0,S16
设等差数列{an}的前n项和为Sn,若-a2013
设Sn为等差数列{an}的前n项和,已知s6=36,Sn=324 ,S(n-6)=144 ,(n>6) ,求n的值
设等差数列an的前n项和为Sn,若Sn=3,S3n=15,则S5n等于?
设等差数列前N项的和为SN,若SN=SM,则S(M+N)=?
数学题设数列An等差数列前n项和为Sn若m不等于n,Sn=m平方,Sm=n平方,求S(m+n)
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
设等比数列{an}的公比为q,前n项和为Sn,若Sn+1,Sn,Sn+2成等差数列,则q的值为
设等比数列{An}的公比为q,前n项和为Sn,若Sn+1,Sn,Sn+2成等差数列,则q的值为()