Question

Даю 100 баллов за скорость!

Answer 1

1)

$(x - 1)(x + 3) = {x}^{2} + 3x - x - 3 = \\ = {x}^{2} + 2x - 3$

2)

$3(x - 3)(x + 1) = (3x - 9)(x + 1) = \\ = 3 {x}^{2} + 3x - 9x - 9 = 3 {x}^{2} - 6x - 9$

3)

$2(x - 1)(x + 3) = (2x - 2)(x + 3) = \\ 2 {x}^{2} + 6x - 2x + 6 = 2 {x}^{2} + 4x + 6$

4)

$(x - 3)(x + 1) = {x}^{2} + x - 3x - 3 = \\ = {x}^{2} - 2x - 3$

Ответ: 2)