1/N(N+I)+1/(N+1)(N+2)+1/(N+2)(N+3)+.+1/(N+9)(N+10)如何做?

快乐希望 1年前 已收到1个回答 举报

ll神枪手 幼苗

共回答了9个问题采纳率:77.8% 举报

1/N(N+I)+1/(N+1)(N+2)+1/(N+2)(N+3)+.+1/(N+9)(N+10)
=1/n-1/(n+1)-1/(n+1)-1/(n+2)+1/(n+2)-1/(n+3)+---+1/(n+9)-1/(n+10)
=1/n-1/(n+10)
=10/[n(n+10)]
=10/(n²+10n)

1年前

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