ta có:
(2x+3)2+(2x−3)2−(2x+3)(4x−6)+xy
= (2x+3)2+(2x−3)2−2(2x+3)(2x-3)+xy
=(2x+3-2x+3)2+xy
=9+xy
\(\left(2x+3\right)^2+\left(2x-3\right)^2-\left(2x+3\right)\left(4x-6\right)+xy\)
\(=\left(2x+3\right)^2+\left(2x-3\right)^2-2\left(2x+3\right)\left(2x-3\right)+xy\)
\(=\left[\left(2x+3\right)^2-2\left(2x+3\right)\left(2x-3\right)+\left(2x-3\right)^2\right]+xy\)
\(=\left(2x+3-2x+3\right)^2+xy\)
\(=6^2+xy\)
\(=36+xy\)