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已知等差数列{bn}中,,且已知a1=3,a3=9.(1)求数列{bn}的通项公式;(2)...
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已知等差数列{b
n}中,
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gg==
)
,且已知a
1=3,a
3=9.
(1)求数列{b
n}的通项公式;
(2)求数列{a
n}的通项公式和前n项和S
n.
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