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-   -   Curve sketching: 2nd derivatives test (https://www.askmehelpdesk.com/showthread.php?t=401603)

  • Oct 1, 2009, 08:06 AM
    akotoh
    Curve sketching: 2nd derivatives test
    Gud day! :)
    I just want to know what is the correct answer in this problem:

    Equation:
    y = 1/3 x^3 - 1/2 x^2 - 2x
    the point of inflection that I got is (1/2 , -3/4) but according to the book its (1/2, -13/12). How do they get that?

    thanks! :)
  • Oct 1, 2009, 08:14 AM
    ArcSine
    Just evaluate the original equation for x = 1/2.
  • Oct 4, 2009, 03:17 AM
    radiation

    I think thr is some error in your ans.. for x=1/2, the only value for y is -13/12..
  • Oct 4, 2009, 04:08 AM
    galactus
    Quote:

    Gud day! :)
    I just want to know what is the correct answer in this problem:

    Equation:

    the point of inflection that i got is (1/2 , -3/4) but according to the book its (1/2, -13/12). How do they get that?

    thanks! :)
    They found the second derivative, set to 0 and solved for x.







    Plug back into original equation:


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