System of equations with matrix brackets

Question

How can this be done in (La)Tex?

Answer 1

Like this? The code is:

\documentclass{article}
\usepackage{amsmath}

    \begin{document}
\[
\underbrace{\begin{bmatrix}
a       &   b       & \dots     &   n       \\
a       &   b       & \dots     &   n       \\
\vdots  &  \vdots   &   \vdots  &   \vdots  \\   
a       &   b       & \dots     &   n       \\
            \end{bmatrix}
            }_{\mathbf{\Phi}}
\underbrace{\begin{bmatrix}
w_1     \\
w_2     \\
\vdots  \\
w_n     \\
            \end{bmatrix}
            }_{\mathbf{w}}
    \approx
\underbrace{\begin{bmatrix}
y_1     \\
y_2     \\
\vdots  \\
y_n     \\
            \end{bmatrix}
            }_{\mathbf{y}}
\]
    \end{document}

Well, right math terms you need to write in corresponding places yourself. It should be simple task :-).

Answer 2

`Enhancing' @Zarko's example a little....

\documentclass{article}
\usepackage{amsmath}
\usepackage{empheq}
\usepackage{xcolor}

\definecolor{myugly}{rgb}{.6, .9, .2}
\newcommand*\myuglybox[1]{%
\colorbox{myugly}{\hspace{1em}#1\hspace{1em}}}

    \begin{document}
\begin{empheq}[box=\myuglybox]{equation}
\underbrace{\begin{bmatrix}
a       &   b       & \dots     &   n       \\
a       &   b       & \dots     &   n       \\
\vdots  &  \vdots   &   \vdots  &   \vdots  \\   
a       &   b       & \dots     &   n       \\
            \end{bmatrix}
            }_{\mathbf{\Phi}}
{\color{red}\underbrace{\begin{bmatrix}
w_1     \\
w_2     \\
\vdots  \\
w_n     \\
            \end{bmatrix}
            }_{\mathbf{w}}}
    \approx
\underbrace{\begin{bmatrix}
y_1     \\
y_2     \\
\vdots  \\
y_n     \\
            \end{bmatrix}
            }_{\mathbf{y}}
\end{empheq}
    \end{document}