98x102x2004=（100-2）*（100+2）*2004=（10000-4）*2004=20040000-8016=20031984
(-2)^50+(-2)^49+(-2)^48+……+(-2)+1
=(-2-1)【(-2)^50+(-2)^49+(-2)^48+……+(-2)+1】/（-2-1）
=【（-2）^51-1】/(-3)
=(2^51+1)/3
│1/3-1/2│+│1/4-1/3│+1/5-1/4│...│1/2006-1/2005│ =1/2-1/3+1/3-1/4+1/4-1/5+...+1/2005-1/2006 =1/2-1/2006 =501/1003