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设数列{bn}的前n项和为Sn,且bn=2-2Sn;数列{an}为等差数列,且a5=14,...
试题详情
设数列{b
n}的前n项和为S
n,且b
n=2-2S
n;数列{a
n}为等差数列,且a
5=14,a
7=20.
(1)求数列{b
n}的通项公式;
(2)若c
n=a
n•b
n,n=1,2,3,…,T
n为数列{c
n}的前n项和.求证:
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2cxW9lh2BKOaFVFWLFSrmcQ3TZM7oNy92hRp+/0a0QIoTfrwQO3Dn/QbgqL26aAQe+D9ehCdY9dV
CxbTmRKQohyqobcV88LySRR535xSdxBIqSkBNyoIGH46Fvnx+CvdaJyYVw9YBvpy7IUWfrSkGRGU
jPLsVwPWV8OWYvHmNS2AnR7rrEpA1CDb3Re1mw0U6wAKwDGTDlAAXdVuFsAUxvamApRA9CVglgZx
/u4EK3pf5svC6LPHoXW1Bi3Js41Vpdj2CNvof0Bb/AD+ADgMJhlGWuf0AAAAAElFTkSuQmCC
)
.
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设数列{bn}的前n项和为Sn,且bn=2-2Sn;数列{an}为等差数列,且a5=14,a7=20.
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(1)求数列{bn}的通项公式;
(2)若cn=an•bn,n=1,2,3,…,Tn为数列{cn}的前n项和.求证:
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设数列{bn}的前n项和为Sn,且bn=2-2Sn;数列{an}为等差数列,且a5=14,a7=20.
(1)求数列{bn}的通项公式;
(2)若cn=an•bn,n=1,2,3,…,Tn为数列{cn}的前n项和.求证:
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设数列{bn}的前n项和为Sn,且bn=2-2Sn;数列{an}为等差数列,且a5=14,a7=20.
(1)求数列{bn}的通项公式;
(2)若cn=an•bn,n=1,2,3,…,Tn为数列{cn}的前n项和.求证:
.
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设数列{bn}的前n项和为Sn,且bn=2-2Sn;数列{an}为等差数列,且a5=14,a7=20.
(1)求数列{bn}的通项公式;
(2)若cn=an•bn,n=1,2,3,…,Tn为数列{cn}的前n项和.求证:
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