Conjugate cannot work in an expected manner for X + I Y Z

Questions
1

This question comes from here. The test code snippet is shown below:

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As you can see, the last one didn’t work as I expected. Any tip/comment/fix for this behavior is highly appreciated.

Regards,
HZ

2

Try:

(I Y Z)\[Conjugate] // ComplexExpand[#, _ \[Element] Reals] &
(X + I Y)\[Conjugate] // ComplexExpand[#, _ \[Element] Reals] &
(X + I Y Z)\[Conjugate] // ComplexExpand[#, _ \[Element] Reals] &
3

Good. It works. Thank you very much for the tip. I also note that the following simple form gives the same result, so it is sufficient:

(I Y Z)\[Conjugate] // ComplexExpand
(X + I Y)\[Conjugate] // ComplexExpand
(X + I Y Z)\[Conjugate] // ComplexExpand

Regards,
HZ

ComplexExpand.nb (3.4 KB)