难.(17 20:56:34)
题目
难.(17 20:56:34)
1/(n)-1/(n+1)=1/n(n+1)
1/(n+1)-1/(n+2)=1/(n+1)(n+2)
1/(n+2)-1/(n+3)=1/(n+2)(n+3)
化简:1/n(n+1)+1/(n+1)(n+2)+1/(n+2)(n+3)+.+1/(n+99)+(n+100)
答案
1/n(n+1)+1/(n+1)(n+2)+1/(n+2)(n+3)+.+1/(n+99)+(n+100)
=1/n-1/(n+1)+1/(n+1)-1/(n+2)+.1/(n+99)-1/(n+100)
=1/n-1/(n+100)
=100/n(n+100)
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