(本小題滿分12分)設(shè)數(shù)列{

}滿足

。
(1)求數(shù)列{

}的通項公式;
(2)令

,求數(shù)列{

}的前n項和

。
解:(1)由已知,當n

1時,

……..2分

,………………………………..……………5分
而

符合上式,所以數(shù)列{

}的通項公式

…………………………….….6分
(2)由

從而

(1)—(2)得:

………………………….9分
即

………………………………………………………………….12分
練習(xí)冊系列答案
相關(guān)習(xí)題
科目:高中數(shù)學(xué)
來源:不詳
題型:解答題
已知數(shù)列

的前

項和為

,點

均在函數(shù)

的圖象上
(1)求數(shù)列

的通項公式
(2)若數(shù)列

的首項是1,公比為

的等比數(shù)列,求數(shù)列

的前

項和

.
查看答案和解析>>
科目:高中數(shù)學(xué)
來源:不詳
題型:解答題
已知無窮數(shù)列

中,

是首項為

,公差為

的等差數(shù)列;

是首項為

,公比為

的等比數(shù)列

,并對任意

,均有

成立,(1)當

時,求

; (2)若

,試求

的值;(3)判斷是否存在

,使

成立,若存在,求出

的值;若不存在,請說明理由.
查看答案和解析>>
科目:高中數(shù)學(xué)
來源:不詳
題型:單選題
等差數(shù)列

的公差為2,若

成等比數(shù)列,則


=( )
查看答案和解析>>
科目:高中數(shù)學(xué)
來源:不詳
題型:單選題
已知等差數(shù)列{

}的前n項和為

,若

,則

=( )
查看答案和解析>>
科目:高中數(shù)學(xué)
來源:不詳
題型:單選題
設(shè)等差數(shù)列

的前

項和為

,若

,

,則

,

,

,

中最大的是( )
查看答案和解析>>
科目:高中數(shù)學(xué)
來源:不詳
題型:解答題
已知等差數(shù)列{
an}的前
n項的和記為
Sn.如果
a4=-12,
a8=-4.
(1)求數(shù)列{
an}的通項公式;
(2)求
Sn的最小值及其相應(yīng)的
n的值;
(3)從數(shù)列{
an}中依次取出
a1,
a2,
a4,
a8,…,

,…,構(gòu)成一個新的數(shù)列{
bn},求{
bn}的前
n項和.
查看答案和解析>>
科目:高中數(shù)學(xué)
來源:不詳
題型:單選題
定義:在數(shù)列{a
n}中,若滿足-=d(n∈N
*,d為常數(shù)),我們稱{a
n}為“比等差數(shù)列”.已知在“比等差數(shù)列”{a
n}中,a
1=a
2=1,a
3=2,則的個位數(shù)字是( )
查看答案和解析>>