(1-1/2002)+(1-1/2002*2)+(1-1/2002*3)+.......+(1-1/2002*2001)+(1-1/2002*2002)
=2002-1/2002×(1+2+3+……+2001+2002)
=2002-1/2002×(1+2002)×2002/2
=2002-2003/2
=2002-1001.5
=1000.5
(1-1/2002)+(1-1/2002*2)+(1-1/2002*3)+.......+(1-1/2002*2001)+(1-1/2002*2002)
=1x2002-1/2002(1+2+3+..........2002)
=2002-1/2002x(1+2002)x2002/2
=2002-2003/2
=4004/2-2003/2
=2001/2
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+..+(1/2001-1/2002) =1-1/2002=2001/2002 1/1*2+1/2*3+1/3*4+.+1/2001*2002=(1/1-