l1/3-1/2l+l1/4-1/3l+l1/5-1/4l+``````+l1/2011+1/2010l
=1/2-1/3+1/3-1/4+1/4-1/5+``````+1/2010-1/2011
=1/2-1/2011
=2009/4022
说明：因为1/3-1/2的结果是负数,而他的绝对值是正数,所以l1/3-1/2l=1/2-1/3.明白我的做法吗?不是啊、同学。你看错题目了。。你把问题打详细点，看不懂你补充的题目规律