I am trying to follow my teacher's instructions to easily compute for a complex conjugate but I get mathematica to actually reveal the complex conjugate besides the word "conjugate" and even with that the outputs don't seem to match my professor's for Quantum mechanics class. I'm not sure if the coding my professor used is no longer valid, but I really would like to get a handle on this for much more complex (no pun intended) functions involving imaginary numbers and such. I appreciate any assistance in this regard.

This a picture I PrtSc for a better look at what I did

My own input and attempt to compute for a complex conjugate

And Here's what my professor was able to do but I can't emulate despite multiple attempts What it's supposed to look like according to my professor I.

Page 2 of what it's supposed to look like according to my professor

  • 1
    $\begingroup$ Use a + I b instead of a + Ib $\endgroup$
    – Carl Woll
    Sep 20, 2020 at 0:28
  • $\begingroup$ Thanks so much Carl, that seemed to do it! You have saved me from pulling my hair out. $\endgroup$ Sep 20, 2020 at 0:32
  • $\begingroup$ Well ok, it worked until I got to Input 6 $\endgroup$ Sep 20, 2020 at 0:38

1 Answer 1


ComplexExpand is powerful.

f[x_] := E^(-(a + I*b) x);
f[x] // ComplexExpand
Conjugate[f[x]] // ComplexExpand
  • $\begingroup$ Thankyou very much $\endgroup$ Sep 20, 2020 at 0:52
  • $\begingroup$ @Biometric09 Yes, you can attach your code in the question. $\endgroup$
    – cvgmt
    Sep 20, 2020 at 0:54
  • $\begingroup$ Can you do that for a comment, such as the one I'm doing now, or would I have to post a new question. Further, if I do post a new question, how do I post the code that I am attempting to do? $\endgroup$ Sep 20, 2020 at 1:01
  • $\begingroup$ @Biometric09 you can edit your question if you wish. Just click the pencil icon. You follow markdown formatting rules, which there should be links to the details of when you are formatting the edit to your question. $\endgroup$ Sep 20, 2020 at 4:54

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