Question: Show that

\[{{\mathbb{R}}^{3}}=span\left( \left[ \begin{matrix} 1 \\ 2 \\ 3 \\ \end{matrix} \right],\,\left[ \begin{matrix} -1 \\ -1 \\ 0 \\ \end{matrix} \right],\,\left[ \begin{matrix} 2 \\ 1 \\ 1 \\ \end{matrix} \right]\, \right)\]