1/x(x+3)+1/(x+3)(x+6)+---+1/(x+27)(x+30）

分类: 作业答案 • 2021-12-29 16:57:53

问题描述：

答

1/x(x+3)+1/(x+3)(x+6)+---+1/(x+27)(x+30）
=[1/x-1/(x+3)+1/(x+3)-1/(x+6)+---+1/(x+27)-1/(x+30）]/3
=[1/x-1/(x+30)]/3
=10/[x(x+30)]