<exercise checkit-seed="0002" checkit-slug="V2" checkit-title="Linear combinations">
<statement>
<p>Consider the following statement.</p>
<ul>
<li>
The vector <m> \left[\begin{array}{c}
-7 \\
6 \\
-1 \\
-9
\end{array}\right] </m>is not
a linear combination of the vectors <m> \left[\begin{array}{c}
2 \\
-3 \\
-3 \\
0
\end{array}\right] , \left[\begin{array}{c}
4 \\
-1 \\
-3 \\
2
\end{array}\right] , \left[\begin{array}{c}
8 \\
-2 \\
-6 \\
4
\end{array}\right] , \left[\begin{array}{c}
12 \\
2 \\
-6 \\
8
\end{array}\right] , \text{ and } \left[\begin{array}{c}
0 \\
-5 \\
-3 \\
-2
\end{array}\right] </m>.
</li>
</ul>
<ol>
<li> Write an equivalent statement using a vector equation.</li>
<li> Explain why your statement is true or false.</li>
</ol>
</statement>
<answer>
<me>\operatorname{RREF} \left[\begin{array}{ccccc|c}
2 & 4 & 8 & 12 & 0 & -7 \\
-3 & -1 & -2 & 2 & -5 & 6 \\
-3 & -3 & -6 & -6 & -3 & -1 \\
0 & 2 & 4 & 8 & -2 & -9
\end{array}\right] = \left[\begin{array}{ccccc|c}
1 & 0 & 0 & -2 & 2 & 0 \\
0 & 1 & 2 & 4 & -1 & 0 \\
0 & 0 & 0 & 0 & 0 & 1 \\
0 & 0 & 0 & 0 & 0 & 0
\end{array}\right] </me>
<ol>
<li>
The vector equation <m> x_{1} \left[\begin{array}{c}
2 \\
-3 \\
-3 \\
0
\end{array}\right] + x_{2} \left[\begin{array}{c}
4 \\
-1 \\
-3 \\
2
\end{array}\right] + x_{3} \left[\begin{array}{c}
8 \\
-2 \\
-6 \\
4
\end{array}\right] + x_{4} \left[\begin{array}{c}
12 \\
2 \\
-6 \\
8
\end{array}\right] + x_{5} \left[\begin{array}{c}
0 \\
-5 \\
-3 \\
-2
\end{array}\right] = \left[\begin{array}{c}
-7 \\
6 \\
-1 \\
-9
\end{array}\right] </m>has no solutions.</li>
<li>
<p><m> \left[\begin{array}{c}
-7 \\
6 \\
-1 \\
-9
\end{array}\right] </m> is not
a linear combination of the vectors <m> \left[\begin{array}{c}
2 \\
-3 \\
-3 \\
0
\end{array}\right] , \left[\begin{array}{c}
4 \\
-1 \\
-3 \\
2
\end{array}\right] , \left[\begin{array}{c}
8 \\
-2 \\
-6 \\
4
\end{array}\right] , \left[\begin{array}{c}
12 \\
2 \\
-6 \\
8
\end{array}\right] , \text{ and } \left[\begin{array}{c}
0 \\
-5 \\
-3 \\
-2
\end{array}\right] </m>.
</p>
</li>
</ol>
</answer>
</exercise>