(本小题满分12分)
已知

为等比数列,

为等差数列

的前n项和,

(1)求

的通项公式;
(2)设

,求

(Ⅰ)

(3分)

(6分)
(Ⅱ)

①

②
①-②得:

(9分)
整理得:

(12分)
练习册系列答案
相关习题
科目:高中数学
来源:不详
题型:解答题
设数列{
n}满足
1=

,
n+1=
n2+
1,

.
(Ⅰ)当

∈(-∞,-2)时,求证:

M;
(Ⅱ)当

∈(0,

]时,求证:

∈M;
(Ⅲ)当

∈(

,+∞)时,判断元素

与集合M的关系,并证明你的结论.
查看答案和解析>>
科目:高中数学
来源:不详
题型:解答题
(本题满分14分)已知数列

中,

,

.
⑴ 求出数列

的通项公式;
⑵ 设

,求

的最大值。
查看答案和解析>>
科目:高中数学
来源:不详
题型:解答题
(本小题满分14分)
等比数列

的各项均为正数,

成等差数列,且

.
(1)求数列

的通项公式;
(2)设

,求数列

的前

项和

.
查看答案和解析>>
科目:高中数学
来源:不详
题型:解答题
在数列{
an}中,
a1=1,当
n≥2时,
an,
Sn,
Sn-

成等比数列.
(1)求
a2,
a3,
a4,并推出
an的表达式;(2)用数学归纳法证明所得的结论;
(3)求数列{
an}前n项的和.
查看答案和解析>>
科目:高中数学
来源:不详
题型:解答题
(本题满分12分)已知等差数列

满足

。
(Ⅰ)求通项

;
(Ⅱ)设

是首项为1,公比为3的等比数列,求数列

的通项公式及其前

项和

.
查看答案和解析>>
科目:高中数学
来源:不详
题型:解答题
(本小题12分)若数列

的前
n 项和
Sn满足:
Sn= 2
an+1.
(1)求

,

,

;
(2)求

的通项公式.
查看答案和解析>>