一道英语的数学题 看不懂啊
the first term of a geometric series is 24 and the common ratio is 5/2.How many consecutive terms must be taken to give a sum of 609?
人气：210 ℃ 时间：2020-02-04 04:23:50
解答
应该是4吧.首项为24,公比为5/2的这么个级数,多少项的和是609?
24*(（5/2）^n-1)/(5/2-1)=609,解得n=4
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