Results 1 to 4 of 4

Math Help - Finding zeros of a polynominal that doesn't factor (and whose zeros are non-integers)

  1. #1
    Newbie
    Joined
    Mar 2013
    From
    United States
    Posts
    1

    Finding zeros of a polynominal that doesn't factor (and whose zeros are non-integers)

    I've got this here . . . x^3 +7x -1 = 0.

    I know it equals x = 0.142 approx, but I found that out by graphing it. I'm stumped as to how to solve it algebraically.

    Any help is much appreciated.

    Thanks!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Junior Member
    Joined
    Apr 2012
    From
    Maryland
    Posts
    27
    Thanks
    3

    Re: Finding zeros of a polynominal that doesn't factor (and whose zeros are non-integ

    Wikipedia has a pretty comprehensive article regarding how to solve a cubic algebraically.

    Cubic function - Wikipedia, the free encyclopedia
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,407
    Thanks
    1294

    Re: Finding zeros of a polynominal that doesn't factor (and whose zeros are non-integ

    You should use a numerical method. Otherwise use the Cubic Formula if you really feel adventurous...
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Mar 2013
    From
    dublin
    Posts
    19
    Thanks
    2

    Re: Finding zeros of a polynominal that doesn't factor (and whose zeros are non-integ

    Yea I'd go with what Prove it said above and that wiki article should help alot. if it helps at all your looking for 3 roots and two of them are complex roots.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. [SOLVED] Why Do You Factor Before Finding The Zeros?
    Posted in the Algebra Forum
    Replies: 2
    Last Post: November 8th 2011, 10:11 AM
  2. Replies: 2
    Last Post: January 27th 2011, 07:03 PM
  3. Finding the zeros
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: September 21st 2009, 05:18 PM
  4. Finding the zeros
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: September 16th 2009, 04:31 AM
  5. finding zeros
    Posted in the Algebra Forum
    Replies: 3
    Last Post: February 3rd 2007, 09:39 AM

Search Tags


/mathhelpforum @mathhelpforum