Algebra help factoring?

4x^2+9+12x-4y^2        write as

4x^2 - 12x  +  9  -  4y^2         factor the first three terms

(2x - 3)(2x - 3)  - 4y^2          simplify

(2x - 3)^2  -  4y^2      we have a difference of squares...so we have

[ (2x  - 3) + 2y ]  [ (2x - 3)  - 2y ]