Chapter 2.9, Problem 14E

In Exercises 13 and 14, find a basis for the subspace spanned by the given vectors. What is the dimension of the subspace?

14. $\left[\begin{array}{l}1\\ -1\\ -2\\ 5\end{array}\right]$, $\left[\begin{array}{c}\begin{array}{l}2\\ -2\\ -1\\ 6\end{array}\end{array}\right]$, $\left[\begin{array}{c}\begin{array}{l}0\\ 2\\ -6\\ 8\end{array}\end{array}\right]$, $\left[\begin{array}{c}\begin{array}{l}-1\\ 4\\ -7\\ 7\end{array}\end{array}\right]$, $\left[\begin{array}{c}\begin{array}{l}3\\ -8\\ 9\\ -5\end{array}\end{array}\right]$