Question

Evaluate
$\left[\begin{array}{c}3\\ 4\\ 1\end{array}\right]\left[\begin{array}{ccc}2& -1& 3\end{array}\right]$

Answer 1

$\left[\begin{array}{c}3\\ 4\\ 1\end{array}\right]\left[\begin{array}{ccc}2& -1& 3\end{array}\right]=\left[\begin{array}{ccc}3\times 2& 3\times (-1)& 3\times 3\\ 4\times 2& 4\times (-1)& 4\times 3\\ 1\times 2& 1\times (-1)& 1\times 3\end{array}\right]$

$=\left[\begin{array}{ccc}6& -3& 9\\ 8& -4& 12\\ 2& -1& 3\end{array}\right]$