1/(456)+1/(567)+1/(678)+……+1/（9899100）=

题目详情

1/(4*5*6)+1/(5*6*7)+1/(6*7*8)+……+1/（98*99*100）=

▼优质解答

答案和解析

247/9900
1/(4*5*6)=1/2[1/(4*5)-1/(5*6)];
1/(5*6*7)=1/2[1/(5*6)-1/(6*7)];
.
最后就只剩下 1/2[1/(4*5)-1/(99*100)]

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