This is LaTeX code:

[latex]
\begin{pmatrix}
1-\mu \\
-1+\mu \\
1 \\
0 \\
\end{pmatrix} + t \begin{pmatrix}
-3 \\
1 \\
0 \\
1 \\
\end{pmatrix}, \ t \in \mathbb{R}
[/latex]