What is the cross product of (0, -1, 2)T with (1, 2, 1)T ?
Evaluation follows the same pattern as before, but the second and third rows have been swapped.
This is the negative of the previous result, demonstrating that
u × v = -(v × u) .
(You saw this before, only done with geometrical vectors).
What does the determinant-like thing look like when you take the cross product of a vector by itself?