Results 1 to 4 of 4

Math Help - Polynomial functions questions?

  1. #1
    Newbie
    Joined
    Nov 2012
    From
    Canada
    Posts
    9
    Thanks
    1

    Polynomial functions questions?

    1. Solve 3x3-13x2+19x-5 = 0 given that there are no integral nor negative roots.
    2. The polynomial function y=x4-11x3+40x2-55x+25. It intersects the x-axis at x=1, x=5, and at two other points.
    Determine these other two x-intercepts.

    Thanks!

    Follow Math Help Forum on Facebook and Google+

  2. #2
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    10,054
    Thanks
    368
    Awards
    1

    Re: Polynomial functions questions?

    Quote Originally Posted by WhatthePatel View Post
    1. Solve 3x3-13x2+19x-5 = 0 given that there are no integral nor negative roots.
    The rational root theorem says the only possible (positive, non-integral) roots are 1/3 and 5/3.

    -Dan
    Last edited by topsquark; January 15th 2013 at 04:12 PM.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    10,054
    Thanks
    368
    Awards
    1

    Re: Polynomial functions questions?

    Quote Originally Posted by WhatthePatel View Post
    2. The polynomial function y=x4-11x3+40x2-55x+25. It intersects the x-axis at x=1, x=5, and at two other points.
    Determine these other two x-intercepts.
    If we have a root at x = 1 then we know that the polynomial has a factor (x - 1). So you can divide (long hand or synthetic division) the polynomial to find that x ^4 - 11x^3 + 40x^2 - 55x + 25 = (x - 1)(x^3 - 10x^2 + 30x - 25)

    So what can you do with the root at x = 5?

    -Dan
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Nov 2012
    From
    Canada
    Posts
    9
    Thanks
    1

    Re: Polynomial functions questions?

    Thank you ^^
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Polynomial questions
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: May 11th 2011, 04:21 AM
  2. Polynomial questions
    Posted in the Algebra Forum
    Replies: 4
    Last Post: January 14th 2011, 05:47 PM
  3. Three more polynomial questions
    Posted in the Algebra Forum
    Replies: 2
    Last Post: May 28th 2008, 06:21 PM
  4. two polynomial questions
    Posted in the Algebra Forum
    Replies: 2
    Last Post: May 28th 2008, 09:52 AM
  5. Another polynomial questions
    Posted in the Algebra Forum
    Replies: 1
    Last Post: February 12th 2008, 10:17 AM

Search Tags


/mathhelpforum @mathhelpforum