Consider the subspace \begin{equation*} W=\spn{\set{ \begin{bmatrix} 2 & 1\\3 & -1 \end{bmatrix} ,\, \begin{bmatrix} 4 & 0\\2 & 3 \end{bmatrix} ,\, \begin{bmatrix} -3 & 1\\2 & 1 \end{bmatrix} }} \end{equation*} of the vector space of $2\times 2$ matrices, $M_{22}$. Is $ C= \begin{bmatrix} -3 & 3\\6 & -4 \end{bmatrix} $ an element of $W$?