Square of 1 / 4 (a + b) - 9 (factorization)

Square of 1 / 4 (a + b) - 9 (factorization)

Original formula = [1 / 2 (a + b) + 3] [1 / 2 (a + b) - 3]
=(1/2a+1/2b+3)(1/2a+1/2b-3)