Помогите с алгеброй(необходимо упростить выражения) 7 класс. ДАЮ 25 БАЛЛОВ

Используем формулы сокращенного умножения

a - b = (a - b)(a + b)

a - b = (a - b)(a + ab + b)

a + b = (a + b)(a - ab + b)

1/

(x - 2)(x + 2x + 4) - (1 + x)(x - x + 1) = (x - 2) - (x + 1) = -9

2/

(x - 3)(x + 3x + 9) - x(x + 1)(x - 1) = (x - 3) - x(x - 1) = x - 27 - x + x = x - 27

3/

a(a - 3)(a + 3) - (a + 2)(a - 2a + 4) = a(a - 3) - (a + 2) = a - 9a - a - 8 = -9a - 8

4/ (a - 1)(a + 1)(a + 1)(a + 1)(a + 1)(a - a + 1)(a + a + 1) = a - 1

по долям 1. 1-ые 2 скобки 2. 3-4-5 скобки 3. 6 и 7 скобки

(a - 1)(a + 1) = a - 1

(a - a + 1)(a + a + 1) =  (a + 1 - a )(a + 1 + a) = (a + 1) - (a ) = a + 2a + 1 - a = a + a + 1

(a - 1)(a + a + 1) = a - 1

(a - 1)(a + 1)(a + 1)(a + 1) = (a - 1)(a + 1)(a + 1)(a + 1) = (a - 1)(a + 1)(a + 1) = (a - 1)(a + 1) = a - 1