# 16y^2-x^2-6x-9. How can I factorise this? I know that -(x^2+6x+9) is equal to -(X+3)^2, and 16y^2 can be written as (4y)^2 but I can't quite get the solution (4y-x-3)(4y+X+3)

##### 1 Answer

Feb 28, 2018

#### Explanation:

First observe that

=

=

Now observe that this is of type

Hence we can write

=