\[g(x) = kx + b;\ \ g(1) = 5;\ \ \]
\[g(3) = - 1.\]
\[\left\{ \begin{matrix} k + b = 5\ \ \ \ \ \ \\ 3k + b = - 1 \\ \end{matrix} \right.\ \text{\ \ }( - )\text{\ \ \ \ }\]
\[\left\{ \begin{matrix} - 2k = 6\ \ \\ b = 5 - k \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ \ \ \ \ }\left\{ \begin{matrix} k = - 3 \\ b = 8\ \ \ \\ \end{matrix} \right.\ \]
\(Ответ:\ k = - 3;\ \ b = 8.\)