a^2-8a+5=0,b^2-8b+5=0
(a-1)^2-6(a-1)-2=0,(b-1)^2-6(b-1)-2=0
(a-1)^2=6(a-1)+2,(b-1)^2=6(b-1)+2
即a-1和b-1是x^2-6x-2=0的两个根,所以
(a-1)+(b-1)=6
(a-1)(b-1)=-2
(b-1)/(a-1)+(a-1)/(b-1)=[(b-1)^2+(a-1)^2]/[(a-1)(b-1)]
={[6(b-1)+2]+[6(a-1)+2]}/[(a-1)(b-1)]
={6[(b-1)+(a-1)]+4}/(-2)
={6*6+4}/(-2)
=-20