a+x的平方=2006,
b+x的平方=2007.
c+x的平方=2008,b=a+1,c=a+2
代入abc=24得
a(a+1)(a+2)=24
a³+3a²+2a-24=0
a³-2a²+5a²+2a-24=0
a²(a-2)+(a-2)(5a+12)=0
(a-2)(a²+5a+12)=0
a²+5a+12=(a+5/2)²+11/4>0
a-2=0
a=2,b=3,c=4
c/ab+b/ac
=4/6+3/8
=25/24