Solution
= Solution
The reverse arrangement is an <outer product>, with entries $a_i b_j$:
$$
\boxed{\mathbf a\mathbf b^T=\begin{pmatrix}2&1\\6&3\end{pmatrix}.}
$$
= Solution
The reverse arrangement is an <outer product>, with entries $a_i b_j$:
$$
\boxed{\mathbf a\mathbf b^T=\begin{pmatrix}2&1\\6&3\end{pmatrix}.}
$$