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Homework Help: Taylor polynomial

  1. Mar 27, 2008 #1
    Hi,

    I want to confirm this:

    a=8 , b=5 , c=7

    Decide the Taylor polynomial of degree 2 in the point (0, a) to the function f (x, y)=sqrt(1+bx+cy). Decide with the aid of Taylor polynomial if the function has a local minimum in (0, a).

    I used the partial derivates:

    df/dx = 5/(2*sqrt(1+5x+7y)) = 5/sqrt(57)
    df/dy = 7/(2*sqrt(1+5x+7y)) = 7/sqrt(57)
    and so on with the rest of the derivates

    And with the all derivates in the taylor polynomial i will get a value different then 0 and that mean that it havent got a minimum.

    Is this the correct way to slove this?
     
  2. jcsd
  3. Mar 28, 2008 #2

    cristo

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    Staff Emeritus
    Science Advisor

    Well, these should be 5/{2sqrt(57)} and 7/{2sqrt(57)}.

    I think you should show some more work-- I can't tell what you've done if I can't see it!
     
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