楼主打错了吧c/zb+b/zc+a/bc-1/a-1/b应该是c/ab+b/ac+a/bc-1/a-1/b-1/c吧
照这样说,应该这样做：
c/ab+b/ac+a/bc-1/a-1/b=c^2+b^2+a^2-bc-ac-2ab/abc
=2c^2+2b^2+2a^2-2bc-2ac-2ba/abc
=（a-b）^2+(b-c)^2+(a-c)^2/2abc
∵a+x^2=2006.b+x^2=2007.c+x^2=2008
∴ a=2006-x^2
b=2007-x^2
c=2008-x^2
∴a-b=-1
b-c=-1
a-c=-2
∴原式=（-1）^2+(-1)^2+(-2)^2/48
=6/48
=1/8