(a²+4a-5)x²-4(a-1)x+3<0
(a+5)(a-1)x²-4(a-1)x+3<0
若A=R即x取任何值都满足上式子
需要抛物线y=(a+5)(a-1)x²-4(a-1)x+3开口向下且与X轴无交点
即（a+5)(a-1)<0
且方程(a+5)(a-1)x²-4(a-1)x+3=0无解
（a+5)(a-1)<0 ===>-5<a<1 .........(1)
△=[4(a-1]²-4(a+5)(a-1)*3 〈0
(a-1)(a-19)<0 ==>1〈a〈19 ........(2)
(1)∩(2) ==>不存在这样的实数a
若A为空集
需要抛物线y=(a+5)(a-1)x²-4(a-1)x+3开口向上且与X轴无交点
同理（a+5)(a-1)>0 ==>a<-5,或a>1 .....(3)
△=[4(a-1]²-4(a+5)(a-1)*3 ≤0
==>1≤a≤19 ....(4)
(3))∩(4)==>1<a≤19
