16. Let A and B be defined by

$$

A = \begin{bmatrix}

1 & 1 & 1 \\

2 & 2 & 2 \\

-1 & 1 & -3

\end{bmatrix}; B = \begin{bmatrix}

0 & 2 & 1 \\

0 & 4 & 2 \\

0 & -2 & -1

\end{bmatrix}.

$$

Show that the column space of B is a subspace of the column space of A.