2n22n的知识精选

若数列{an}是正项数列,且++…+=n2+n,则a1++…+等于(  )A.2n2+2n   B.n2+2n...
问题详情:若数列{an}是正项数列,且++…+=n2+n,则a1++…+等于()A.2n2+2n   B.n2+2n     C.2n2+n     D.2(n2+2n)【回答】A【考点】8H:数列递推式.【分析】利用数列递推关系可得an,再利用等差数列的求和公式即可得出.【解...
若数列{an}是正项数列,且++…+=n2+n,则a1++…+等于(  )A.2n2+2n     B.n2+...
问题详情:若数列{an}是正项数列,且++…+=n2+n,则a1++…+等于()A.2n2+2n     B.n2+2n         C.2n2+n        D.2(n2+2n)【回答】A  知识点:数列题型:选择题...
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