Verified answer

Ответ:

1) (x + 2)(x - 9) - 3x(3 - 2x) = x² - 9x + 2x - 18 - 9x + 6x² = 7x² - 16x - 18

2) (a + 5)(a - 2) + (a + 4)(a - 5) = a² - 2a + 5a - 10 + a² - 5a + 4a - 20 = 2a² + 2a - 30

3) (y - 8)(2y + 1) - (3y + 1)(y - 6) = 2y² + y - 16y - 8 - (3y² - 18y + y - 6) = 2y² + y - 16y - 8 - 3y² + 18y - y + 6 = -y² + 2y - 2