$\textsf{Determine if the columns of the matrix span $R^4$.}\\$

$\textit{Then, find a column of the matrix that can be deleted and yet have the remaining matrix columns still span $R^4$.}$

$$\left[\begin{array}{rrrrr}

12& -7& 11& -9 &5 \\

-9& 4& -8& 7& -3 \\

-6& 11& -7& 3&-9\\

4&-6&10&-5&12

\end{array}\right]$$

ok we are supposed to solve this

using SAGE

I presume the first step is row reduction

quidence requested☕