$7x^2 + 11x - 18 = 0$
$\begin{equation*} \begin{cases} x_1 + x_2 = -\frac{b}{a} &\\ x_1x_2 = \frac{c}{a} & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 + x_2 = -\frac{11}{7} &\\ x_1x_2 = \frac{-18}{7} & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 + x_2 = -1\frac{4}{7} &\\ x_1x_2 = -2\frac{4}{7} & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 = -2\frac{4}{7} &\\ x_2 = 1 & \end{cases} \end{equation*}$
Ответ: $-2\frac{4}{7}; 1$.

$9x^2 - 5x - 4 = 0$
$\begin{equation*} \begin{cases} x_1 + x_2 = -\frac{b}{a} &\\ x_1x_2 = \frac{c}{a} & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 + x_2 = -\frac{-5}{9} &\\ x_1x_2 = \frac{-4}{9} & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 + x_2 = \frac{5}{9} &\\ x_1x_2 = -\frac{4}{9} & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 = -\frac{4}{9} &\\ x_2 = 1 & \end{cases} \end{equation*}$
Ответ: $-\frac{4}{9}; 1$.