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...
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...
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...