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Homework Help: Trouble completing the square on the integral

  1. Dec 6, 2011 #1
    1. The problem statement, all variables and given/known data


    2. Relevant equations

    3. The attempt at a solution
    The negative sign in front of x^2 is giving me trouble.

    When i complete the square i get; [itex]\sqrt{}-x^2-4x+4 -4[/itex]

    There's some algebra that i don't understand.
  2. jcsd
  3. Dec 6, 2011 #2


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    First, complete the square for [itex]x^2+4x\,.[/itex] Then take the negative of the result.
  4. Dec 7, 2011 #3


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    [itex]-x^2- 4x= -(x^2+ 4x)[/itex]

    Now complete the square for [itex]x^2+ 4x[/itex].
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