互为相反数 所以ab-2=0,b-1=0,得出a=2,b=1原式=1/1*2+1/2*3+1/3*4+....+1/2002*2003+1/2003*2004 =[(1/1-1/2)+(1/2-1/3)+(1/3-1/4)+...+(1/2002-1/2003)+(1/2003+1/2004)] =1/1+1/2004 =1+1/2004 =2005/2004哎呀，搞得我头都晕了
