Test 1
Testing
Test 1: Section 1
\[\begin{equation}
\frac{\partial \mathbf{U}}{\partial t}= \boldsymbol{c}+\text{this text is inside math mode.}
\label{Test1-eq:01}
\end{equation}\]
Referencing Eq.\(\eqref{Test1-eq:01}\).
\[\begin{eqnarray}
\hat{a}x+\hat{b}y&=&\hat{c}\label{Test1-eq:02}\\
\hat{d}x+\hat{e}y&=&\hat{f}.\label{Test1-eq:03}
\end{eqnarray}\]
We can write Eqs.\(\eqref{Test1-eq:02}\) and \(\eqref{Test1-eq:03}\) as
\[\begin{equation}
\begin{bmatrix}
\hat{a}&\hat{b}\\
\hat{d}&\hat{e}
\end{bmatrix}\begin{bmatrix}
x\\
y
\end{bmatrix}=\begin{bmatrix}
\hat{c}\\
\hat{f}
\end{bmatrix},
\end{equation}\]
where \(\hat{a},\ldots, \hat{f}\) have \(\underline{\textbf{constant}}\) values.
\({\color{red}12}\) is colored using command ${\color{red} 12}$