Question 612893
ab + 2a + 3b + 6 


(ab + 2a) + (3b + 6 )


a(b + 2) + (3b + 6 )


a(b + 2) + 3(b + 2)


(a + 3)(b + 2)



So ab + 2a + 3b + 6 completely factors to <font color="red">(a + 3)(b + 2)</font>