因为A=(-1,5) A∩B=(-1,4)
所以B=(k,4) k∈(-∞,-1]
x^2-2x-m<0
(x-1)^2-(1+m)<0m>=-1
[x-1+(1+m)^(1/2)][x-1-(1+m)^(1/2)]<0
1-(1+m)^(1/2)1+(1+m)^(1/2)=4
m=8
1-(1+m)^(1/2)=-2<-1
所以m=8