∵4x^2+4(a-1)x+a^2-2a-3=0
∴4x^2+4(a-1)x+(a-3)(a+1)=0
∴[2x+(a-3)][2x+(a+1)]=0
∴2x+a-3=0或2x+a+1=0
∴x1=(3-a)/2,x2=-(a+1)/2.