- #1
Diomarte
- 26
- 0
Homework Statement
Show that: [p,x] = -iħ,
Show that: [p,x^n] = -niħ x^(n-1), n>1
Show that: [p, A] = -iħ dA/dx
Where p = -iħ d/dx, and A = A(x) is a differentiable function of x.
Homework Equations
[p,x] = px - xp;
The Attempt at a Solution
So far I understand part of each of these, to begin with the first part:
[p,x] = [(-iħ d/dx) (x)] - [(x) (-iħ d/dx)]
- From this, I simply get -iħ on the left hand side, which is already my answer that I'm looking for, but I do not understand how the right hand side simply cancels out or goes away, maybe I'm mistaken in my understanding of commutators?
For the 2nd part, I as well have -niħ x^(n-1) on the left, yet again what my goal is, and thus same problem with right hand side... Any assistance in this would be greatly appreciated, thank you.