$2x^2 - 5x + 3 = 0$
$\begin{equation*} \begin{cases} x_1 + x_2 = -\frac{b}{a} &\\ x_1x_2 = \frac{c}{a} & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 + x_2 = -\frac{-5}{2} &\\ x_1x_2 = \frac{3}{2} & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 + x_2 = 2,5 &\\ x_1x_2 = 1,5 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 = 1,5 &\\ x_2 = 1 & \end{cases} \end{equation*}$
Ответ: 1; 1,5.

$2x^2 + 5x + 3 = 0$
$\begin{equation*} \begin{cases} x_1 + x_2 = -\frac{b}{a} &\\ x_1x_2 = \frac{c}{a} & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 + x_2 = -\frac{5}{2} &\\ x_1x_2 = \frac{3}{2} & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 + x_2 = -2,5 &\\ x_1x_2 = 1,5 & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 = -1,5 &\\ x_2 = -1 & \end{cases} \end{equation*}$
Ответ: −1,5; −1.

$16x^2 - 23x + 7 = 0$
$\begin{equation*} \begin{cases} x_1 + x_2 = -\frac{b}{a} &\\ x_1x_2 = \frac{c}{a} & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 + x_2 = -\frac{-23}{16} &\\ x_1x_2 = \frac{7}{16} & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 + x_2 = \frac{23}{16} = 1\frac{7}{16} &\\ x_1x_2 = \frac{7}{16} & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 = \frac{7}{16} &\\ x_2 = 1 & \end{cases} \end{equation*}$
Ответ: $\frac{7}{16}; 1$.

$-8x^2 - 19x + 27 = 0$
$\begin{equation*} \begin{cases} x_1 + x_2 = -\frac{b}{a} &\\ x_1x_2 = \frac{c}{a} & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 + x_2 = -\frac{-19}{-8} &\\ x_1x_2 = \frac{27}{-8} & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 + x_2 = -\frac{19}{8} = -2\frac{3}{8} &\\ x_1x_2 = \frac{27}{-8} = -3\frac{3}{8} & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} x_1 = -3\frac{3}{8} &\\ x_2 = 1 & \end{cases} \end{equation*}$
Ответ: $-3\frac{3}{8}; 1$.