\begin{exercise}{V2}{Linear combinations}{0007}
\begin{exerciseStatement}
Consider the following statement.
\begin{itemize}
\item The vector \( \left[\begin{array}{c}
8 \\
5 \\
-11 \\
11
\end{array}\right] \)is a linear combination of the vectors \( \left[\begin{array}{c}
0 \\
1 \\
3 \\
-1
\end{array}\right] , \left[\begin{array}{c}
3 \\
1 \\
-2 \\
1
\end{array}\right] , \left[\begin{array}{c}
-1 \\
-3 \\
-1 \\
-3
\end{array}\right] , \left[\begin{array}{c}
1 \\
-2 \\
-2 \\
0
\end{array}\right] , \text{ and } \left[\begin{array}{c}
4 \\
-1 \\
2 \\
1
\end{array}\right] \).
\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}\[\operatorname{RREF} \left[\begin{array}{ccccc|c}
0 & 3 & -1 & 1 & 4 & 8 \\
1 & 1 & -3 & -2 & -1 & 5 \\
3 & -2 & -1 & -2 & 2 & -11 \\
-1 & 1 & -3 & 0 & 1 & 11
\end{array}\right] = \left[\begin{array}{ccccc|c}
1 & 0 & 0 & 0 & \frac{12}{5} & -3 \\
0 & 1 & 0 & 0 & -\frac{1}{5} & 2 \\
0 & 0 & 1 & 0 & -\frac{6}{5} & -2 \\
0 & 0 & 0 & 1 & \frac{17}{5} & 0
\end{array}\right] \]
\begin{enumerate}[(a)]
\item The vector equation \( x_{1} \left[\begin{array}{c}
0 \\
1 \\
3 \\
-1
\end{array}\right] + x_{2} \left[\begin{array}{c}
3 \\
1 \\
-2 \\
1
\end{array}\right] + x_{3} \left[\begin{array}{c}
-1 \\
-3 \\
-1 \\
-3
\end{array}\right] + x_{4} \left[\begin{array}{c}
1 \\
-2 \\
-2 \\
0
\end{array}\right] + x_{5} \left[\begin{array}{c}
4 \\
-1 \\
2 \\
1
\end{array}\right] = \left[\begin{array}{c}
8 \\
5 \\
-11 \\
11
\end{array}\right] \)has a solution.
\item
\( \left[\begin{array}{c}
8 \\
5 \\
-11 \\
11
\end{array}\right] \) is a linear combination of the vectors \( \left[\begin{array}{c}
0 \\
1 \\
3 \\
-1
\end{array}\right] , \left[\begin{array}{c}
3 \\
1 \\
-2 \\
1
\end{array}\right] , \left[\begin{array}{c}
-1 \\
-3 \\
-1 \\
-3
\end{array}\right] , \left[\begin{array}{c}
1 \\
-2 \\
-2 \\
0
\end{array}\right] , \text{ and } \left[\begin{array}{c}
4 \\
-1 \\
2 \\
1
\end{array}\right] \).
\end{enumerate}
\end{exerciseAnswer}
\end{exercise}