skip a line aside a matrix [closed]

Question

Well, This is what I tried to compile If you compile it the sequence of number will be next to the matrix, but I want it to be in other line. Do you know how to do that space? Thank you so much in advance.

\documentclass[]{book}
\usepackage{amssymb}

\begin{document}
\[
\beta= \left[ \begin{array}{c}
   \beta_0      \\
   \beta_1      \\
   \vdots  \\
   \beta_k
   \end{array}
    \right],
\textbf{\epsilon}= \left[ \begin{array}{c}
            \epsilon_1      \\
            \epsilon_2      \\
            \vdots  \\
            \epsilon_n\\
           \end{array}
    \right]
    \]

    1234

\end{document}

Answer 1

The \textbf command won't make \epsilon boldfaced, as it is made for insertion of ordinary text inside math formulae. You should use the \bm command (from the bm package), which is made for math mode. Here is a correct code:

\documentclass[]{book}
\usepackage{amssymb, bm}
\begin{document}
\[
\beta= \left[ \begin{array}{c}
   \beta_0      \\
   \beta_1      \\
   \vdots  \\
   \beta_k
\end{array}
\right],
\quad
\bm{\epsilon} = \left[ \begin{array}{c}
        \epsilon_1      \\
        \epsilon_2      \\
        \vdots  \\
        \epsilon_n\\
       \end{array}
\right]
\]

1234

\end{document}

and

By the way, I once asked how some can load fine antialiased images instead of a miserable png. What's the trick, please?