How to factorize X2 - (a + A2) x + a3 < 0 How does it become (x-a) (x-a2) < 0

How to factorize X2 - (a + A2) x + a3 < 0 How does it become (x-a) (x-a2) < 0

x2-(a+a2)x+a3<0
x2-(a+a2)x+[(-a)*(-a2)]<0
(x-a)(x-a2)<0