x^2+(2a+1)x-3a^2-a<0
x^2+(2a+1)x-a(3a+1)<0
(x-a)(x+(3a+1))<0
若a>-(3a+1),即:a>-1/4,则解集为:
-(3a+1)
若a<-(3a+1),即:a<-1/4,则解集为:
a
若a=-(3a+1),即:a=-1/4,则不等式无解
x^2+(2a+1)x-3a^2-a<0
x^2+(2a+1)x-a*(3a+1)<0
(x-a)(x+3a+1)<0
x-a>0且x+3a+1<0,a
或者x-a<0且x+3a+1>0,-3a-1
当然,如果a取定一值后,就只会有一解!