Question

What is the product

Answer 1

Step-by-step explanation:

all work is pictured and shown

Answer 2

You simply have to multiply each entry by -4:

$-4\cdot \left[\begin{array}{c}8\\-1\\-5\\9\end{array}\right] = \left[\begin{array}{c}-4\cdot8\\-4\cdot(-1)\\-4\cdot(-5)\\-4\cdot9\end{array}\right] = \left[\begin{array}{c}-32\\4\\20\\-36\end{array}\right]$