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问题: 初二分式

1/(a+1)(a+3)+1/(a+3)(a+5)+1/(a+5)(a+7)...+1/(a+2003)(a+2005)

解答:

因为:1/(a+1)(a+3)=1/2*(1/(a+1)-1/(a+3))
1/(a+3)(a+5)=1/2*(1/(a+3)-1/(a+5))
..........
1/(a+2003)(a+2005)=1/2*(1/(a+2003)-1/(a+2005))
所以:1/(a+1)(a+3)+1/(a+3)(a+5)+1/(a+5)(a+7)...+1/(a+2003)(a+2005)
=1/2*(1/(a+1)-1/(a+3)+1/(a+3)-1/(a+5))+...........+1/(a+2003)-1/(a+2005))=1/2*(1/(a+1)-1/(a+2005))