test
\[\begin{align*} {\mathbf X}^\top = \left[\begin{array}{rrrr} 2 & 6 & 5 & 1\\ -2 & 6 & 4 & -7\\ -8 & -4 & 3 & 6 \\ 6 & 9 & -7 & 7 \\ -7 & 6 & 8 & -1 \end{array}\right] \end{align*}\]
\[\begin{align*} {\mathbf X}^\top = \left[\begin{array}{rrrr} 2 & 6 & 5 & 1\\ -2 & 6 & 4 & -7\\ -8 & -4 & 3 & 6 \\ 6 & 9 & -7 & 7 \\ -7 & 6 & 8 & -1 \end{array}\right] \end{align*}\]