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Numerical Method Set of questions

  1. Oct 28, 2007 #1
    Hi, i'm currently stuck with 2 questions:

    1. Given that the negative root of the equation [tex]f(x) = x^{3} - 7(x) + 5[/tex]
    lies between a and a + 1 where a is an integer write down a value of a

    2. Show that the equation [tex]e^{-x} = x^{2}[/tex] has a root between x = 0.70 and 0.71

    Thanks :)
     
  2. jcsd
  3. Oct 28, 2007 #2

    rock.freak667

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    Well for both you need to find values that make f(x) differ in sign..
     
  4. Oct 28, 2007 #3
    do i use trial and error? Or is there a more sophisticated way?
     
  5. Oct 28, 2007 #4

    rock.freak667

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    For the first one you can just use trial an error with negative values...but I can simply see one negative value of x that will make f(x)= ...
     
  6. Oct 29, 2007 #5
    f(0) = 5
    f(1) = -1

    so a = 0
     
  7. Oct 29, 2007 #6

    rock.freak667

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    But you see...between 0 and 1 would mean that the root is +ve so you must find f(-1) or f(-2) etc for the root to be -ve
     
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