根号(a-1)+(ab-2)^2=0a-1=0ab-2=0a=1b=21/ab+1/(a+1)(b+1)+1/(a+2)(b+2)+……+1/(a+2004)(b+2004)=1/1*2+1/2*3+1/3*4+-------+1/2005*2006=1-1/2+1/2-1/3+1/3-1/4+------+1/2005-1/2006=1-1/2006=2005/2006