When you meet a simple math problem, please use the properties of square difference and complete square to do it. This is the simplification of job hunting.
Original formula =2b? +a？ -B? -(a? +2ab+b？ )
=2b？ +a？ -B? -a？ -2ab-b？
=-2ab
When a =-3 and b = half:
Original formula =(-2)x(-3)x half.
=3
I wish you a happy life and progress in your study!