By the way, can anyone explain me what @Robert Israel meant by his comment: "You should ask your teacher what kind of work would be needed to be shown to get full points on this type of question."
It should be noted that he deleted an answer to the effect of "oh ho! Qualifying your answer, I see. Are you just trying to leave yourself an escape route?" I'd love to see that explained, but maybe amWhy will choose not to explain it.
@cnmesr you've said that the professor "allows calculators" during exams. However, based on your question, it is unclear whether your professor allows you to use the calculator's matrix-calculation ability. I think you should go to your professor and ask "if I put something like this on an exam, would it get full credit?"
Ah alright, understood. The problem is they usually never reply to my mails (and no I'm not asking them, let's say strange questions as I recently asked here). Additionally, we are on semester vacation now ^^ Anyway, I will give it a try tomorrow.