# I need your opinions on Zettili's solution of an exercise

1. Sep 29, 2015

### KostasV

1. The problem statement, all variables and given/known data
(Uploaded photo from Zettili Quantum Mechanics - Chapter 3 - Solved problems 3.4 and 3.5)
Check at problem 3.4 the relation that he gives between operator A and state φn.
Now check the relation that he uses in problem 3.5 between A and φn again.
They are different while on the announcement of prob 3.5 he does not mention any change of this relation.

2. Relevant equations

3. The attempt at a solution
Is there any misprint or am i that dumb that cannot understand some change of the relation that he implies?

Last edited: Sep 29, 2015
2. Sep 29, 2015

### blue_leaf77

I think that's not a misprint for the answer of prob 3.5 follows as a consequence of the written relation between $\hat{A}$ and $|\phi_n\rangle$ in that problem. My guess is that he forgot that in the previous problem 3.4 he defined $|\phi_n\rangle$'s as the eigenstates of $\hat{A}$.

3. Sep 29, 2015

### KostasV

So, in problem 3.5 he probably wanted to change the relation between $\hat{A}$ and $|\phi_n\rangle$ to $\hat{A}$ $|\phi_n\rangle$ = n $\alpha_o\$ $|\phi_{n+1}\rangle$ (in order not to be anymore eigenstates of $\hat{A}$ ) but forgot to mention it?

4. Sep 30, 2015

### blue_leaf77

Yeah, probably.

5. Sep 30, 2015

### KostasV

Thanks for your response to my issue !