摘要:等差数列中..则( ) A.1 B. C. D.2
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设等差数列{an}的公差为2,前n项和为Sn,则下列结论中正确的是( )
A、Sn=nan-3n(n-1) | B、Sn=nan+3n(n-1) | C、Sn=nan-n(n-1) | D、Sn=nan+n(n-1) |
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A、Sn=nan-3n(n-1) | B、Sn=nan+3n(n-1) | C、Sn=nan-n(n-1) | D、Sn=nan+n(n-1) |