1*2*3分之2加2*3*4分之2.28*29*3 - 知识问答

1*2*3分之2加2*3*4分之2.28*29*30分之2怎解

1个回答

2/(1*2*3)+2/(2*3*4)+…………+2/(28*29*30)
=[1/(1*2) - 1/(2*3)] + [1/(2*3) - 1/(3*4)] +…………+[1/(28*29) - 1/(29*30)]
=1/(1*2) - 1/(29*30)
=1/2 - 1/870
=434/870
=217/435

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