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Math Help - Have I done this manipulation correctly?

  1. #1
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    Have I done this manipulation correctly?

    I started with this



    and rewrote it as this, factoring out sum(ei)



    Is this correct? What I am unsure about is the bottom of the fraction, should it be sum(xj-xbar) or sum(xi-xbar)?

    It's a question in which the final answer has (xj-xbar) on the bottom of that fraction (once you use common denominator) I am trying to establish if it is a typo.
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  2. #2
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    Re: Have I done this manipulation correctly?

    No, that is not correct. The x_i terms depend upon i and are also in the sums.
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  3. #3
    Junior Member
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    Re: Have I done this manipulation correctly?

    Oh, so I cant even do that manipulation...

    The final answer that I had to derive was:


    Last edited by Wevans2303; December 23rd 2012 at 02:10 PM.
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