1. The problem statement, all variables and given/known data I am basically trying to show that LxLy-LyLx=i(hbar)Lz 2. Relevant equations Lx=yPz-zPy Ly=zPx-xPz 3. The attempt at a solution I get to the end where I have i(hbar)Lz-z*y*PxPz+z*xPyPz. How do I get these last two terms to cancel out? I am not too strong in operator math (it hasnt been taught to me, jsut assumed I can do it), so I dont know if the d/dz part of the Pz operator can still apply to a z that is to the left of it, but if it does then I get LxLy-LyLx=2*i(hbar)Pz which is wrong according to my book.... Can anyone help?