若a+x^2=2004,b+x^2=2005,c+x^2=2006,且abc=12,求a/bc+b/ac+c/ab-1/a-1/b-1/c的值.

a-b=2004-2005=-1
b-c=2005-2006=-1
c-a=2006-2004=2
a/bc+b/ac+c/ab-1/a-1/b-1/c
=(a^2+b^2+c^2-bc-ac-ab)/abc
=[(a-b)^2+(b-c)^2+(c-a)^2]/2abc
=(1+1+4)/(2*12)
=6/24
=1/4