Simplifying expression

[oberfeli]

Your response does not help whatsoever and apparently didnt catch your attention as much as the lectures you attended.
In the first place why would I use a CAS?
Right, to save time.
Simple matrices calculations may be easy, but even in that case the HP Prime didnt deliver the expected result. I asked for help simplifying a expression in general as for other calculations doing the calculation manually ( why even bother using a calculator, human mind is obviously superior, it attended lectures) is not that easy and time efficient. Also a CAS calculator may be off in some edge cases but in general and in 99,9% of the time it should be right, at least in the year of 2021.

Verifying important results by hand is important, but doing everything manually is plainly stupid and that kind of response makes no sense whatsoever in a calculator forum.
Btw the CAS calculator of Texas Instruments has no problem with this kind of simplification at all.