
求教大家,这道题应该怎么写,不会写啊
1个回答
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1 + 2 +3 + 4 +... +n = n * (1+n)/2
所以题目=2 * [1/(1*2) + 1/(2*3) + .. + 1/(100*101)]
= 2 * [(1 - 1/2) + (1/2 - 1/3) + .. + (1/100 - 1/101)]
= 2 * (1 - 1/101) = 200/101
所以题目=2 * [1/(1*2) + 1/(2*3) + .. + 1/(100*101)]
= 2 * [(1 - 1/2) + (1/2 - 1/3) + .. + (1/100 - 1/101)]
= 2 * (1 - 1/101) = 200/101
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