\begin{exercise}{V2}{Linear combinations}{0004}
\begin{exerciseStatement}
Consider the following statement.
\begin{itemize}
\item The vector \( \left[\begin{array}{c}
-5 \\
-4 \\
2 \\
3
\end{array}\right] \)is a linear combination of the vectors \( \left[\begin{array}{c}
-1 \\
-1 \\
-3 \\
1
\end{array}\right] , \left[\begin{array}{c}
4 \\
-2 \\
-5 \\
-1
\end{array}\right] , \left[\begin{array}{c}
-2 \\
-2 \\
-6 \\
2
\end{array}\right] , \left[\begin{array}{c}
-4 \\
8 \\
22 \\
-2
\end{array}\right] , \text{ and } \left[\begin{array}{c}
-4 \\
2 \\
5 \\
1
\end{array}\right] \).
\end{itemize}
\begin{enumerate}[(a)]
\item Write an equivalent statement using a vector equation.
\item Explain why your statement is true or false.
\end{enumerate}
\end{exerciseStatement}
\begin{exerciseAnswer}\[\operatorname{RREF} \left[\begin{array}{ccccc|c}
-1 & 4 & -2 & -4 & -4 & -5 \\
-1 & -2 & -2 & 8 & 2 & -4 \\
-3 & -5 & -6 & 22 & 5 & 2 \\
1 & -1 & 2 & -2 & 1 & 3
\end{array}\right] = \left[\begin{array}{ccccc|c}
1 & 0 & 2 & -4 & 0 & 0 \\
0 & 1 & 0 & -2 & -1 & 0 \\
0 & 0 & 0 & 0 & 0 & 1 \\
0 & 0 & 0 & 0 & 0 & 0
\end{array}\right] \]
\begin{enumerate}[(a)]
\item The vector equation \( x_{1} \left[\begin{array}{c}
-1 \\
-1 \\
-3 \\
1
\end{array}\right] + x_{2} \left[\begin{array}{c}
4 \\
-2 \\
-5 \\
-1
\end{array}\right] + x_{3} \left[\begin{array}{c}
-2 \\
-2 \\
-6 \\
2
\end{array}\right] + x_{4} \left[\begin{array}{c}
-4 \\
8 \\
22 \\
-2
\end{array}\right] + x_{5} \left[\begin{array}{c}
-4 \\
2 \\
5 \\
1
\end{array}\right] = \left[\begin{array}{c}
-5 \\
-4 \\
2 \\
3
\end{array}\right] \)has a solution.
\item
\( \left[\begin{array}{c}
-5 \\
-4 \\
2 \\
3
\end{array}\right] \) is not a linear combination of the vectors \( \left[\begin{array}{c}
-1 \\
-1 \\
-3 \\
1
\end{array}\right] , \left[\begin{array}{c}
4 \\
-2 \\
-5 \\
-1
\end{array}\right] , \left[\begin{array}{c}
-2 \\
-2 \\
-6 \\
2
\end{array}\right] , \left[\begin{array}{c}
-4 \\
8 \\
22 \\
-2
\end{array}\right] , \text{ and } \left[\begin{array}{c}
-4 \\
2 \\
5 \\
1
\end{array}\right] \).
\end{enumerate}
\end{exerciseAnswer}
\end{exercise}