已知/XY-2/(这是绝对值的符号)与/Y-1/互为相反数.

1:绝对值永远大于等于0
|xy-2|+|y-1|=0
|xy-2|=0 ,|y-1|=0
xy=2
y-1=0
y=1,x=2
2:1/xy+1/(x+1)(y+1)+...+1/(x+2009)(y+2009)
=1/2*1+1/3*2+1/4*3+...+1/2011*2010
=1-1/2+1/2-1/3+1/3-1/4+...+1/2010-1/2011
=1-1/2011
=2010/2011