作业帮 > 数学 > 作业

|已知|ab-2|与(b-1)2互为相反数,试求式子1/ab+1/(a+1)(b+1)+1/(a+2)(b+2)+...

来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/05/14 09:13:53
|已知|ab-2|与(b-1)2互为相反数,试求式子1/ab+1/(a+1)(b+1)+1/(a+2)(b+2)+...+1/(a+2008)(b+2008)的值.
|ab-2|与(b-1)2互为相反数
ab-2=0
b-1=0
b=1
a=2
1/ab+1/(a+1)(b+1)+1/(a+2)(b+2)+...+1/(a+2008)(b+2008)
=-1/a+1/b-1/(a+1)+1/(b+1)-...-1/(a+2008)+1/(b+2008)
=-[1/a+1/a+1+.+1/a+2008]+1/b+1/(b+1)+.+1/(b+2008)
=-1/2-1/3-...-1/2010+1/1+1/2+.+1/2009
=1-1/2010
=2009/2010