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已知{bn}是公比大于1的等比数列,它的前n项和为Sn,若S3=14,b1+8,3b2,b...
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已知{b
n}是公比大于1的等比数列,它的前n项和为S
n,若S
3=14,b
1+8,3b
2,b
3+6成等差数列,且a
1=1,
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3GPAhHiPP+sNYsCECCLSzNxj4D9VjG3opaimPQAAAABJRU5ErkJggg==
)
(n≥2).
(1)求b
n;
(2)求数列{na
n}的前n项和S
n.
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