丨ab-2丨+(b+1)的平方=0时
b+1=0 b=-1
ab-2=0 a=-2
1/ab+1/(a-1)(b-1)+.+1/(a-2011)(b-2011)
=1/[(-1)x(-2)+1/[(-1-1)x(-2-1)]+……+1/[(-1-2011)x(-2-211)]
=1/(1x2)+1/(2x3)+……+1/(2012x2013)
=1-1/2+1/2-1/3+……+1/2012-1/2013
=1-1/2013
=2012/2013答案上写的是负的这个绝对正确，可能你的题目有问题。好吧、好吧、