б) -m² – 8m + 9 > 0;

б) $$-m^2 - 8m + 9 > 0$$

Умножим на -1:

$$m^2 + 8m - 9 < 0$$

$$m^2 + 8m - 9 = 0$$

$$D = 64 + 36 = 100$$

$$m_1 = \frac{-8 + 10}{2} = 1$$

$$m_2 = \frac{-8 - 10}{2} = -9$$

$$(m - 1)(m + 9) < 0$$

___-9____1____

+ - +

$$m \in (-9; 1)$$

Ответ: $$m \in (-9; 1)$$