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交错级数收敛的问题

2011-09-19 17:57:33| 分类：数学答疑辅导 | 标签： |举报 |字号大中小订阅

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问：徐老师请教您个问题，交错级数敛散性判断标准是：1.通项趋于零，2.逐项递减。
那如果是在满足条件1但项数一定大时才逐项递减，之前时增时减的能判断它收敛吗？

答：可以，因为级数是否收敛与级数的前有限项无关（见下面的性质3）。所以只要从某一项开始级数满足那两个条件即可。

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