答：
A/(x-3)+B/(x+1)=(4x-8)/(x^2-2x-3)
A/(x-3)+B/(x+1)
=(4x-8)/[(x+1)(x-3)]
=(x-2)*[1/(x-3)-1/(x+1)]
=(x-2)/(x-3)-(x-2)/(x+1)
所以：
A=x-2
B=-(x-2)
所以：A/B=-1