Question

bracket 3 a b + C whole square minus bracket 3 a b minus C whole square

Answer 1

${(3ab \: + c)}^{2} - {(3ab \: - c)}^{2} \\ (9 {a}^{2} {b}^{2} + {c}^{2} + 6abc) - (9 {a}^{2} {b}^{2} + {c}^{2} - 6abc) \\ 9 {a}^{2} {b}^{2} + {c}^{2} + 6abc - 9 {a}^{2} {b}^{2} - {c}^{2} + 6abc \\ 0 + 0 + 12abc \\ = 12abc$