I'm afraid I'm completely stuck even with the hint! I cannot find any example of anything similar to this in my book. And since you were hiding that hint, I can only assume it's supposed to be a rather short and easy step in the proof.
Yeah, I've tried to set x=0 which gives me E_1= 3/2 \dfrac{\hbar ^2}{2mL^2} which i don't find satisfy the E_1 = 3/2 \hbar \omega .
And on my paper i ofcourse had the x^2 part of the portential.
Homework Statement
The wave function \psi_0 (x) = A e^{- \dfrac{x^2}{2L^2}}
represents the ground-state of a harmonic oscillator. (a) Show that \psi_1 (x) = L \dfrac{d}{dx} \psi_0 (x) is also a solution of Schrödinger's equation. (b) What is the energy of this new state? (c) From a look at...