1/(x+1)(x+2)=1/(x+1)-1/(x+2)
原式左边展开等于[1/x-1/(x+1)]+[1/(x+1)-1/(x+2)]+……+[1/(x+2009)-1/(x+2010)]+1/x+2010=
2/x-1/(x+2010)+2010=2010所以x=-4020