Factorize:
a2+6a+9−4b2
(a+2b+3)(a−2b+3)
(a+3+2b)(a+3−2b)
⇒a2+6a+9−4b2
=(a2+6a+9)−(4b2)
=(a2+3a+3a+9)−(4b2)
=(a(a+3)+3(a+3)−(4b2)
=[(a+3)(a+3)−(4b2)]
=[(a+3)2−(4b2)]
=[(a+3)2−(2b)2]
Let (a+3)=x and 2b=y
⇒[x2−y2]=(x+y)(x−y)
Subtituting the values back we get
(a+3+2b)(a+3−2b)