Prove Hermitian with two different wave functions

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pfollansbee
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Homework Statement



Let [tex]ψ(r)= c_n ϕ_n (r) + c_m ϕ_m (r)[/tex] where [tex]ϕ_n(r)[/tex] and [tex]ϕ_m (r)[/tex] are independent functions.
Show that the condition that  is Hermitian leads to
[tex]∫ψ_m (r)^* Âψ_n (r)dr = ∫Â^* ψ_m (r)^* ψ_n (r)dr[/tex]

Homework Equations



[tex]∫ψ(r)^*  ψ(r)dr = ∫Â^* ψ(r)^* ψ(r)dr[/tex]

The Attempt at a Solution



It is obvious to me that if
[tex]<m|\hat A|n> = <\hat A m|n>[/tex]
then
[tex]<m|\hat A|n> = <n|\hat A|m>^*[/tex]

My professor gave me a hint and said that I need to expand these out and show that they are equal. This is where my problem lies. I have no idea how to expand these out. I have tried a few ways, like setting
[tex]\phi _m = (\psi -c_n \phi _n)/c_m[/tex]
This certainly did not seem like the correct approach to me.

Maybe someone here can give me another hint as to how this goes. I have asked my professor three times to talk to me about it, but he seems content in misunderstanding me and talking about other problems that we have already solved.
 
Hmm no replies... oh well. Here is the solution that I came up with. Just in case anyone else happens to happen upon a similar problem, this may help.
 
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  • Handwritten derivation showing that Hermitian operator leads to the integral of psi_m* A psi_n equals the integral of (A psi_m)* psi_n, with expansion in terms of c_n, c_m and bra-ket terms, concluding with matched coefficients.
    solution.png
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