Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Newton-Raphson Formula question

  1. May 29, 2012 #1
    Find the smallest positive root of the equation x^4 + x^2 - 80= 0 correct to two decimal places. Use the Newton-Raphson process.

    How would I go about finding the smallest positive root? What I was thinking is using x = 3 as x = 3 is the largest number that would be close to 0 (for the equation), then finding an approximation for that, is that correct?

  2. jcsd
  3. May 29, 2012 #2


    User Avatar
    Science Advisor
    Gold Member

    1) Independent of the question asked, can you see that the equation is trivially solvable exactly analytically (no need for Newton-Raphson)?

    2) For a numeric solution, a start value of 3 looks fine. I assume (hope) you know how to apply Newton-Raphson from there.
    Last edited: May 29, 2012
  4. May 30, 2012 #3
    I'm perfectly aware it is solvable from that form, and I do know how to apply Newton-Raphson. Thanks.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook