设Sn是等差数列(An)的前n项和,若S3/S6=1/3,求S6/S12=?
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设Sn为等差数列{An}的前n项和,求证:{Sn/n}是等差数列
设Sn是等差数列{an}的前n项和,求证:若正整数m,n,p成等差数列,则Sm/m,Sn/n,Sp/p也成等差数列.
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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
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设{an}是等差数列前n项和为Sn,若S4>=10,S5
数列{an}满足a(n+1)+an=4n-3,若{an}是等差数列,(1)求{an}的通项公式(2)设Sn是{an}的前n项和,数列{an}满足a(n+1)+an=4n-3,若{an}是等差数列,(1)求{an}的通项公式(2)设Sn是{an}的前n项和,且a1=1,求S(2n+1)
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设等差数列an的前n项和为Sn,若S4>=10,S5