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问题: 化简

1/X(x+1)+1/(x+1)(x+2)+1/(x+2)(x+3)+……+1/(x+8)(x+9)

解答:

1/X(x+1)+1/(x+1)(x+2)+1/(x+2)(x+3)+……+1/(x+8)(x+9)=
[(1/X)-(x+1)]+[1/(x+1)-1/(x+2)]+[1/(x+2)-1/(x+3)]+……+[1/(x+8)-1/(x+9)]=
(1/X)-[1/(x+9)]=
8/[X(x+9)]