To simplify: (3x−2y)(3x+4y)−(3x+2y)(3x−2y)(−4y2+6xy)
Using identity (a+b)(a−b)=a2−b2,
(3x+2y)(3x−2y)=9x2−4y2
So, the numerator can be simplified as
(3x−2y)(3x+4y)−(3x+2y)(3x−2y)
=(9x2+6xy−8y2)−[9x2−4y2]
=−4y2+6xy
Then,
(3x−2y)(3x+4y)−(3x+2y)(3x−2y)(−4y2+6xy)⇒−4y2+6xy−4y2+6xy=1