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Homework Help: Taylor Polynomial

  1. Aug 16, 2009 #1
    Using P2(x,y), find a quadratic approximation to ln(1.25) to 4 decimal places.

    The original function is f(x,y)=ln(x2 + y2) and is about the point (1,0).

    I calculated P2 to be y2-x2+4x-3

    however I don't know how to find a quadratic approximation. Do I just set say x=1 and y=.5?

    Any help would be great!
  2. jcsd
  3. Aug 18, 2009 #2

    Gib Z

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    Homework Helper

    Thats not exactly it, but on the right track. Just any values of x and y that make x^2 + y^2 = 1.25. (1, 0.5) would work, but would not give you 4dp accuracy. Something like (1.1, 0.2) would work somewhat better, but still nowhere near 4dp accuracy.

    EDIT: I don't know how they expect you to get 4dp accuracy, seeing as even x^2=1.25 and y=0 gives only 2dp accuracy. Sorry
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