Factorize:
9 – a2 + 2ab – b2
We have,
= [9 – (a2 – 2ab + b)2]
We can also write the expression as:
= [(3)2 – (a – b)2]
Now,
Using identity: a2 – b2 = (a – b)(a + b)
Hence,
The given expression can be factorized as: 
17
Factorize:
9 – a2 + 2ab – b2
We have,
= [9 – (a2 – 2ab + b)2]
We can also write the expression as:
= [(3)2 – (a – b)2]
Now,
Using identity: a2 – b2 = (a – b)(a + b)
Hence,
The given expression can be factorized as: