Выражение: 1) (а-2)(а-1)-а(а+1) 2) (b-5)(b+10)+(b+6)(b-8) 3) (2c+3)(3c++7)(2c-7) 4) 3d+5)(5d--3)(2-8d)

1) (a - 2)(a - 1) - a(a + 1) = a² - a - 2a + 2 - a² - a = 2 - 4a

2) (b - 5)(b + 10) + (b + 6)(b - 8) = b² + 10b - 5b - 50 + b² - 8b + 6b - 48 =

= 2b² + 3b - 98

3) (2c + 3)(3c + 2) - (2c + 7)(2c - 7) = 6c² + 4c + 9c + 6 - 4c² + 49 =

= 2c² + 13c + 55

4) (3d + 5)(5d - 1) - (d - 3)(2 - 8d) = 15d² - 3d + 25d -5 - 2d + 8d² + 6 - 24d = 23d² - 4d + 1