Question

Factorise.

9x²y² − 16

Answer 1

9x²y² − 16

On writing it as follows:

= (3xy)² − (4)² 

Using the identity a² − b² = (a − b) (a + b)

= (3xy − 4) (3xy + 4)

= [a² − b² = (a − b) (a + b)]