.a(a+1）分之1+(a+1)(a+2)分之1+（a+2)(a+3)+``````+(a+2004)(a+2005）分

lixiao_08062022-10-04 11:39:542条回答

.a(a+1）分之1+(a+1)(a+2)分之1+（a+2)(a+3)+``````+(a+2004)(a+2005）分之1

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sixsun0818 共回答了14个问题 | 采纳率85.7%: 1/(a+n)(a+n+1)=1/(a+n)-1/(a+n+1)
a(a+1）分之1+(a+1)(a+2)分之1+（a+2)(a+3)+``````+(a+2004)(a+2005）分之1
=1/a-1/(a+1)+1/(a+1)-1/(a+2)+.+1/(a+2004)-1/(a+2005)
=1/a-1/(a+2005)
=2004/(a^2+2005a); 1年前

ypczlb 共回答了1个问题 | 采纳率: 1; 1年前

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