1. The problem statement, all variables and given/known data I've attached my past paper question, which contains the relevant integral identity too. 3. The attempt at a solution This question is relatively simple, yet I can't seem to complete it. I used the schrodinger equation which is: -(ħ²/2m)[tex]\nabla^2[/tex]u + Vu = Eu I then used the identity given in the question, to differentiate the wavefunction w.r.t to r twice. (In this part I had to differentiate by products since there was another factor of r). Differentiating the wavefunction twice gave me: (Z²/a²).r.u When I put this into the schrodinger equation above, knowing V and E, I dont get the correct answer.