\begin{exercise}{E1}{Linear systems, vector equations, and augmented matrices}{0010}
\begin{exerciseStatement}
Consider the vector equation.
\[ x_{1} \left[\begin{array}{c}
1 \\
0 \\
1 \\
0
\end{array}\right] + x_{2} \left[\begin{array}{c}
6 \\
1 \\
-1 \\
2
\end{array}\right] + x_{3} \left[\begin{array}{c}
5 \\
2 \\
-4 \\
2
\end{array}\right] = \left[\begin{array}{c}
-7 \\
-1 \\
0 \\
-2
\end{array}\right] \]
\begin{enumerate}[(a)]
\item Write a system of scalar equations corresponding to this vector equation.
\item Write an augmented matrix corresponding to this vector equation.
\end{enumerate}
\end{exerciseStatement}
\begin{exerciseAnswer}
\begin{enumerate}[(a)]
\item \[\begin{matrix}
x & + & 6 \, y & + & 5 \, z & = & -7 \\
& & y & + & 2 \, z & = & -1 \\
x & - & y & - & 4 \, z & = & 0 \\
& & 2 \, y & + & 2 \, z & = & -2 \\
\end{matrix}\]
\item \[ \left[\begin{array}{ccc|c}
1 & 6 & 5 & -7 \\
0 & 1 & 2 & -1 \\
1 & -1 & -4 & 0 \\
0 & 2 & 2 & -2
\end{array}\right] \]
\end{enumerate}
\end{exerciseAnswer}
\end{exercise}