1x2/1+2x3/1+3x4/1+4x5/1+5x6/1+6x7/1+7x8/1+8x9/1+9x10/1

老格2022-10-04 11:39:541条回答

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迷惘80后共回答了22个问题 | 采纳率90.9%: 1x2/1+2x3/1+3x4/1+4x5/1+5x6/1+6x7/1+7x8/1+8x9/1+9x10/1
＝1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90
=(1-1/2)+(1/2-1/3)+……+(1/8-1/9)+(1/9-1/10)
=1-1/10
=9/10; 1年前

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