Задание 4. Упростите выражение: 1)(x + 2)(x + 10) - 2x(4-3x) = 2)(a-2)(a +5) + (a + 3)(a - 4) = 3)(y-9) (2y + 1) + (3-y) (2y - 1) = 4)(4x-2)(4x - 3) - (2x-10)(7x + 1) =

Решение:

1. $$ (x + 2)(x + 10) - 2x(4-3x) = x^2 + 10x + 2x + 20 - 8x + 6x^2 = 7x^2 + 4x + 20 $$
   Ответ: $$7x^2 + 4x + 20$$
2. $$ (a-2)(a +5) + (a + 3)(a - 4) = a^2 + 5a - 2a - 10 + a^2 - 4a + 3a - 12 = 2a^2 + 2a - 22 $$
   Ответ: $$2a^2 + 2a - 22$$
3. $$ (y-9) (2y + 1) + (3-y) (2y - 1) = 2y^2 + y - 18y - 9 + 6y - 3 - 2y^2 + y = -10y - 12 $$
   Ответ: $$-10y - 12$$
4. $$ (4x-2)(4x - 3) - (2x-10)(7x + 1) = 16x^2 - 12x - 8x + 6 - (14x^2 + 2x - 70x - 10) = 16x^2 - 20x + 6 - 14x^2 + 68x + 10 = 2x^2 + 48x + 16 $$
   Ответ: $$2x^2 + 48x + 16$$