题目内容

等比数列前n项和为Sn,有人算得S1="8," S­­2="20," S3="36," S4=65,后来发现有一个数算错了,错误的是(   )
A.S1B.S2C.S­3D.S4
C

试题分析:根据题意,由于等比数列前n项和为Sn,有人算得S1="8," S­­2="20," S3=36,如果S1="8," S­­2- S1=12,,故S3="38," S4=65成立,故可知错误的是S­3,选C.
点评:解决的关键是根据等比数列前几项来确定正确性,属于基础题。
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