(4;0); (5;5).
y = kx + b
$\begin{equation*} \begin{cases} 0 = 4k + b &\\ 5 = 5k + b | * (-1) & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 0 = 4k + b &\\ -5 = -5k - b & \end{cases} \end{equation*}$
4k + b − 5k − b = −5
−k = −5
k = 5
5k + b = 5
b = 5 − 5k
b = 5 − 5 * 5
b = 5 − 25
b = −20
Ответ: y = 5x − 20

(4;−3); (9;−5).
y = kx + b
$\begin{equation*} \begin{cases} -3 = 4k + b &\\ -5 = 9k + b | * (-1) & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} -3 = 4k + b &\\ 5 = -9k - b & \end{cases} \end{equation*}$
4k + b − 9k − b = −3 + 5
−5k = 2
k = 2 : (−5)
k = −0,4
4k + b = −3
b = −4k − 3
b = −4 * (−0,4) − 3
b = 1,6 − 3
b = −1,4
Ответ: y = −0,4x − 1,4

(−5;−7); (−3;0).
y = kx + b
$\begin{equation*} \begin{cases} -7 = -5k + b &\\ 0 = -3k + b | * (-1) & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} -7 = -5k + b &\\ 0 = 3k - b & \end{cases} \end{equation*}$
−5k + b + 3k − b = −7
−2k = −7
k = −7 : (−2)
k = 3,5
3k − b = 0
b = 3k
b = 3 * 3,5
b = 10,5
Ответ: y = 3,5x + 10,5

(−8;1); (−1;4).
y = kx + b
$\begin{equation*} \begin{cases} 1 = -8k + b &\\ 4 = -k + b | * (-1) & \end{cases} \end{equation*}$
$\begin{equation*} \begin{cases} 1 = -8k + b &\\ -4 = k - b & \end{cases} \end{equation*}$
−8k + b + k − b = 1 − 4
−7k = −3
$k = \frac{3}{7}$
−k + b = 4
b = 4 + k
$b = 4 + \frac{3}{7}$
$b = 4\frac{3}{7}$
Ответ: $y = \frac{3}{7}x + 4\frac{3}{7}$