是實(shí)數(shù).的等差中項(xiàng).是.的等比中項(xiàng).則的范圍是 .查看更多

 

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等差數(shù)列{an}中,a2=4,其前n項(xiàng)和Sn滿足Sn=n2+λn(λ∈R)
(Ⅰ)求實(shí)數(shù)λ的值,并求數(shù)列{an}的通項(xiàng)公式;
(Ⅱ)若數(shù)列{
1Sn
+bn}
是首項(xiàng)為λ、公比為2λ的等比數(shù)列,求數(shù)列{bn}的前n項(xiàng)的和Tn

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等差數(shù)列{an}中,a2=4,其前n項(xiàng)和Sn滿足

(Ⅰ)求實(shí)數(shù)λ的值,并求數(shù)列{an}的通項(xiàng)公式;

(Ⅱ)若數(shù)列是首項(xiàng)為λ、公比為2λ的等比數(shù)列,求數(shù)列{bn}的前n項(xiàng)的和Tn

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等差數(shù)列{an}中,a2=4,其前n項(xiàng)和Sn滿足

(Ⅰ)求實(shí)數(shù)λ的值,并求數(shù)列{an}的通項(xiàng)公式;

(Ⅱ)若數(shù)列是首項(xiàng)為λ、公比為2λ的等比數(shù)列,求數(shù)列{bn}的前n項(xiàng)的和Tn

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等差數(shù)列{an}中,a2=4,其前n項(xiàng)和Sn滿足Sn=n2+λn(λ∈R).

(Ⅰ)求實(shí)數(shù)λ的值,并求數(shù)列{an}的通項(xiàng)公式;

(Ⅱ)若數(shù)列是首項(xiàng)為λ、公比為2λ的等比數(shù)列,求數(shù)列{bn}的前n項(xiàng)的和Tn

查看答案和解析>>

等差數(shù)列{an}中,a2=4,其前n項(xiàng)和Sn滿足Sn=n2+λn(λ∈R).

(Ⅰ)求實(shí)數(shù)λ的值,并求數(shù)列{an}的通項(xiàng)公式;

(Ⅱ)若數(shù)列是首項(xiàng)為λ、公比為2λ的等比數(shù)列,求數(shù)列{bn}的前n項(xiàng)的和Tn

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