[SOLVED] raising and lowering operators 1. The problem statement, all variables and given/known data http://img125.imageshack.us/img125/2923/85098487ch9.jpg [Broken] 3. The attempt at a solution I expand a+ and a-, introduce the wavefunction and then substitute the values given at the very end to give: http://img187.imageshack.us/img187/8224/37075232fm3.jpg [Broken] This is where I'm stuck. I can't see how epsilon = 2mE/hbar comes into the equation. Are my initial calculations even correct?