Без комментариев) ааааа

${(x - 4)}^{2} - 16 = {(x - 4)}^{2} - {4}^{2} = (x - 4 - 4)(x - 4 + 4) = x(x - 8)$

$10a + {(a - 5)}^{2} = 10a + {a}^{2} + {5}^{2} - 10a = {a}^{2} + 25$

${(3m - 7n)}^{2} - {(3m + 7n)}^{2} = 9 {m}^{2} + 49 {n}^{2} - 42mn - (9 {m}^{2} + 49 {n}^{2} + 42mn) = 9 {m}^{2} + 49 {n}^{2} - 42mn - 9 {m}^{2} - 49 {n}^{2} - 42mn = - 84mn$

${(6a - 3b)}^{2} - {(9a + 2b)}^{2} = 36 {a}^{2} + 9 {b}^{2} - 36ab - (81 {a}^{2} + 4 {b}^{2} + 36ab) = 36 {a}^{2} + 9 {b}^{2} - 36ab - 81 {a}^{2} - 4 {b}^{2} - 36ab = - 45a \\ {a}^{2} - 5 {b}^{2} - 72ab$

$b(b - 3) - {(b - 4)}^{2} = {b}^{2} - 3b - ( {b}^{2} + 16 - 8b) = {b}^{2} - 3b - {b}^{2} - 16 + 8b= 5b - 16$