记数列{an}的前n项和为Sn,且Sn=2(an-1),则a2()A.4B.2C.1D.-2-数学

题目简介

记数列{an}的前n项和为Sn,且Sn=2(an-1),则a2()A.4B.2C.1D.-2-数学

题目详情

记数列{an}的前n项和为Sn,且Sn=2(an-1),则a2(  )
A.4B.2C.1D.-2
题型:单选题难度:中档来源:龙岩模拟

答案

∵S1=2(a1-1),
∴a1=2
∵a1+a2=2(a2-1),
∴a2=4
故选A

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