Christian Lawson-Perfect

I just noticed a fact that I hadn't seen before, which I'll illustrate with two examples:

$\begin{vmatrix} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{vmatrix} = 0$

$\begin{vmatrix} 0 & 1 & 2 \\ 3 & 6 & 9 \\ 12 & 16 & 20 \end{vmatrix} = 0$

What's the pattern?

A Mastodon instance for maths people. The kind of people who make $\pi z^2 \times a$ jokes.
Use $ and $ for inline LaTeX, and $ and $ for display mode.