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1又1/2+3又1/4+5又1/8+···+[(2n-1)+1/2的n次方]=
人气:386 ℃ 时间:2020-06-06 21:46:00
解答
=[1+3+……+(2n-1)]+(1/2+1/4+……+1/2^n)
=[1+(2n-1)]*n/2+1/2*(1-1/2^n)/(1-1/2)
=n²+1-1/2^n
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