=1/2(1-1/3)+1/2(1/3-1/5)+……+1/2(1/2001-1/2003)
=1/2[1+(1/3-1/3)+(1/5-1/5)+……+(1/2001-1/2001)-1/2003]
=1/2(1-1/2003)
=1/2×2002/2003
=1001/2003哦。我知道了，刚才没认真看题目。谢了不用客气