1:绝对值永远大于等于0|xy-2|+|y-1|=0|xy-2|=0 ,|y-1|=0xy=2y-1=0y=1,x=22:1/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=2010/2...