规律为-1/nx1/(n+1)=-1/n+1/(n+1)
(-1x1/2)+(-1/2x1/3)+(-1/3x1/4)+...+(-1/2010x1/2011)
=(-1+1/2)+(-1/2+1/3)+(-1/3+1/4)+...+(-1/2010+1/2011)
=-1+1/2011
=-2010/2011
规律为-1/nx1/(n+1)=-1/n+1/(n+1)
(-1x1/2)+(-1/2x1/3)+(-1/3x1/4)+...+(-1/2010x1/2011)
=(-1+1/2)+(-1/2+1/3)+(-1/3+1/4)+...+(-1/2010+1/2011)
=-1+1/2011
=-2010/2011