Expectation value problem

Discussion in 'Math' started by boks, Nov 16, 2008.

  1. boks

    Thread Starter Active Member

    Oct 10, 2008
    218
    0
    1. The problem statement, all variables and given/known data

    Calculate \Delta x = \sqrt{\left\langle(x - \left\langle x \right\rangle )^2 \right\rangle} if \left\langle x \right\rangle = 0 and \left\langle x^2 \right\rangle = a^2(\frac{\pi - 6}{12 \pi^2})

    2. The attempt at a solution

    \left\langle(x - \left\langle x \right\rangle )^2 \right\rangle = \left\langle x^2 - 2x \left\langle x \right\rangle + \left\langle x \right\rangle ^2 \right\rangle

    How can I proceed here?
     
  2. steveb

    Senior Member

    Jul 3, 2008
    2,433
    469
    Wouldn't the next logical step be to take advantage of the fact that \left\langle x \right\rangle = 0 ?

    The problem looks a whole lot simpler once you do that. :)
     
  3. boks

    Thread Starter Active Member

    Oct 10, 2008
    218
    0
    Lol, stupid of me.
     
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