(a^2-3a+1)/(a-3)
=(a^2-6a+9+3a-8)/(a-3)
=[(a-3)^2+3(a-3) +1]/(a-3)
=(a-3) +3 + 1/(a-3)
又因为a0
所以(a^2-3a+1)/(a-3)=(a-3) + 1/(a-3) +3