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Homework Help: Convert a derivative back to original function

  1. Apr 28, 2007 #1
    The problem statement, all variables and given/known data

    f'(x) = 5x^2 + 7x -3

    The attempt at a solution

    i divided 5 by 3 to get 5/3
    added 1 to exponent of 5x^2
    made 7x to 7x^2 and -3 to -3x

    to get

    f(x) = 5/3 x^ 3 + 7x^2 - 3x

    i get this answer, but is there and other way to get the original function and other possible answers (or a helpfull website related to this)
    Last edited: Apr 28, 2007
  2. jcsd
  3. Apr 28, 2007 #2
    The middle term is 7/2 x^2.

    You can confirm your answer by differentiation back to f'(x).

    Note that you could also add any number to your expression and you would still get the same derivative, because, e.g. d/dx 42 =0.

    You're actually doing 'integration', though you may not know it yet. Wikipediate or Google it.
  4. Apr 28, 2007 #3


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    Science Advisor

    You said you "made 7x to 7x^2 and -3 to -3x" but you didn't do that in your answer.

    Believe it or not, derivatives and "anti- derivatives" are calculus, not "pre"- calculus. I'm going to move this to the calculus homework forum.
  5. Apr 28, 2007 #4
    oh yea, sry, and thx for your answers
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