1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How do i find the roots of this polynomial?

  1. Jun 24, 2013 #1
    x^3-5x-6=0

    i've tried the p/q calculations in accordance with the rational roots theorem but i've yet to find the answers...
     
  2. jcsd
  3. Jun 24, 2013 #2

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    You can either:
    1. Use trial and error to find a solution.
    2. Graph the equation in order to estimate a solution.
    3. Use the formula for the roots of a cubic equation (most complicated approach).

    See: http://en.wikipedia.org/wiki/Cubic_function
     
  4. Jun 24, 2013 #3

    D H

    User Avatar
    Staff Emeritus
    Science Advisor

    4. Use an approximation scheme such as regula falsi, secant method, or Newton's method.

    The rational root theorem says yields a small number of candidate rational roots. Not a single one of those candidates will yield a root. That doesn't mean there aren't any roots. It just means the root/roots aren't rational numbers.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted