1. The problem statement, all variables and given/known data Using the results of the previous problem, find [x,p2 ] and from that determine [x,p2 ][itex]\psi[/itex](x) 2. Relevant equations The solution to the previous problem was [A,BC]=[A,B]C+B[A,C] 3. The attempt at a solution As I'm suppose to use the results of the previous problem I think what I need to do is [x,pp]=[x,p]p+p[x,p] But that doesn't really seem right to me... shouldn't this lead me to an identity (it doesn't say but usually in a QM problem p is momentum and this would seem to be leading to a wave equation in momentum space). If I really am approaching this the correct way, then how should I treat [x,p2 ][itex]\psi[/itex](x)?