觀察下列各式
(1) 1/1*2+1/2*3+1/3*4=1-1/2+1/2-1/3+1/3-1/4=3/4
(2) 1/1*3+1/3*5+1/5*7+1/7*9
=1/2{2/1*3+2/3*5+2/5*7+2/7*9}
=1/2{1-1/3+1/3-1/5+1/5-1/7+1/7-1/9}=1/2*8/9=4/9
根據(jù)以上觀察,計(jì)算
1/1*4+1/4*7+1/7*10+.+1/2002*2005+1/2005*2008