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Homework Help: Commutators for functions of operators (momentum/position)

  1. May 16, 2012 #1
    1. The problem statement, all variables and given/known data

    show that [x,f(p_x)] = i [itex]\hbar[/itex] d/d(p_x) f(p_x)

    2. Relevant equations

    x is the position operator in the x direction, p_x is the momentum operator; i [itex]\hbar[/itex]
    [x, p_x]=xp-px
    3. The attempt at a solution
    I'm stuck. maybe chain rule for d/dx and d/d(p_x)...? But I don't see how I'd do it...
  2. jcsd
  3. May 17, 2012 #2
    Never mind - I had to reqresent it as a power series, and then it was easier
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