設(shè)數(shù)列{
an}是公差不為零的等差數(shù)列,
Sn是數(shù)列{
an}的前
n項(xiàng)和,且
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=9
S2,
S4=4
S2,求數(shù)列的通項(xiàng)公式.
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科目:高中數(shù)學(xué)
來源:不詳
題型:解答題
(本小題滿分12分)已知數(shù)列
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,
定義其倒均數(shù)是
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。
(1)求數(shù)列{
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}的倒均數(shù)是
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,求數(shù)列{
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}的通項(xiàng)公式
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;
(2)設(shè)等比數(shù)列
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的首項(xiàng)為-1,公比為
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,其倒數(shù)均為
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,若存在正整數(shù)k,使得當(dāng)
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恒成立,試找出一個(gè)這樣的k值(只需找出一個(gè)即可,不必證明)
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科目:高中數(shù)學(xué)
來源:不詳
題型:解答題
(本小題滿分14分)
在數(shù)列
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與
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中,

,數(shù)列
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的前
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項(xiàng)和
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滿足
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,
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為
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與
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的等比中項(xiàng),
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.
(Ⅰ)求
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的值;
(Ⅱ)求數(shù)列
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與

的通項(xiàng)公式;
(Ⅲ)設(shè)
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.證明
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.
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科目:高中數(shù)學(xué)
來源:不詳
題型:解答題
數(shù)列
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為等差數(shù)列,
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為正整數(shù),其前
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項(xiàng)和為
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,數(shù)列

為等比數(shù)列,且
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,數(shù)列
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是公比為64的等比數(shù)列,
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.
(1)求
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;
(2)求證
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.
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科目:高中數(shù)學(xué)
來源:不詳
題型:填空題
已知數(shù)列
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,
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,

,

,
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,…,這個(gè)數(shù)列的特點(diǎn)是從第二項(xiàng)起,每一項(xiàng)都等于它的前后兩項(xiàng)之和,則這個(gè)數(shù)列的前

項(xiàng)之和
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=
.
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科目:高中數(shù)學(xué)
來源:不詳
題型:解答題
某商店投入38萬元經(jīng)銷某種紀(jì)念品,經(jīng)銷時(shí)間共60天,為了獲得更多的利潤,商店將每天獲得的利潤投入到次日的經(jīng)營中,市場調(diào)研表明,該商店在經(jīng)銷這一產(chǎn)品期間第

天的利潤
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(單位:萬元,
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),記第
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天的利潤率

,例如
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小題1:求

的值;
小題2:求第
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天的利潤率

;
小題3:該商店在經(jīng)銷此紀(jì)品期間,哪一天的利潤率最大?并求該天的利潤率。
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科目:高中數(shù)學(xué)
來源:不詳
題型:解答題
已知等差數(shù)列的前
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項(xiàng)和為
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,前
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項(xiàng)和為

,求前
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項(xiàng)和.
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科目:高中數(shù)學(xué)
來源:不詳
題型:單選題
數(shù)列

滿足
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="1,"
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=
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,且
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(
n≥2),
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則
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等于( )
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