Factorization a square (B-C) + 4 (C-D) - 2Ac + 2Ab

Factorization a square (B-C) + 4 (C-D) - 2Ac + 2Ab

D in (B-C) + 4 (C-D) - 2Ac + 2Ab must be B, otherwise there is no factorization
If B, the original formula = (A-4 + 2a) (C-D)