数列的前n项和为Sn,已知a15,且nSn+12n(n+1)+(n+1)Sn(,则与过点P(n,an)和点Q(n+2,an+1) (的直线平行的向量可以是 ( )
A.(1 , 2) | B.(, 2) | C.(2 , | D.(4 , 1) |
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数列的前n项和为Sn,已知a15,且nSn+12n(n+1)+(n+1)Sn(,则与过点P(n,an)和点Q(n+2,an+1) (的直线平行的向量可以是 ( )
A.(1 , 2) | B.(, 2) | C.(2 , | D.(4 , 1) |
试题篮
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