摘要：2．若{an}是公差为1的等差数列.则{a2n-1+2a2n}是 ( ) A．公差为3的等差数列 B．公差为4的等差数列 C．公差为6的等差数列 D．公差为9的等差数列 解析:设{an}的公差为d.则d＝1.设cn＝a2n-1+2a2n.则cn+1＝a2n+1+2a2n+2.cn+1-cn＝a2n+1+2a2n+2-a2n-1-2a2n＝6d＝6.选择C. 答案:C

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