Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.

Let f(x)= x^3 -2x-2...Newton-Raphson type question??

Find an interval of the form [n,n+1] such that f is guaranteed to have a zero c in [n, n+1], and give a reason for your choice.

Also, from your value of n in the first part, let c1=n. Then use the Newton-Raphson method to find c2.

Thanks a lot.

1 Answer

Relevance
  • 5 years ago

    f'(x) = 3x^2 - 2

    3x^2 - 2 = 0

    3x^2 = 2

    x^2 = 2/3

    x = ±sqrt(2/3)

    x = sqrt(2/3) - min; x = -sqrt(2/3) - max

    f(-sqrt(2/3)) = -0.911 < 0

    f(sqrt(2/3) = -3.089 < 0

    lim(x->+oo)f(x) = +oo =>f(2) = 2>0 => f(x) = 0 x ϵ [sqrt(2/3), 2]

    c1 = sqrt(2/3)

Still have questions? Get your answers by asking now.