Решите плииз. Срооочно

1. $3a(a - 1) - {a}^{2} = \\ = 3 {a}^{2} - 3a- {a}^{2} = \\ = 2 {a}^{2} - 3a$

Ответ : б.

$2(x - 1) - 3x = 5(2 - x) \\2x - 2 - 3x = 10 - 5x \\ 2x - 3x + 5x = 10 - 2 \\ 4x = 8 \\ x = \frac{8}{4} \\ x = 2$

Ответ : б

$3(a - 1)(a + 8) = \\ = 3 \times ( {a}^{2} + 8a - a - 8) = \\ = 3 {a}^{2} + 24a - 3a - 24 = \\ = 3 {a}^{2} + 21a - 24 \: . \\$