Results 1 to 2 of 2

Math Help - Intervals of a trinomial...

  1. #1
    Newbie
    Joined
    Mar 2008
    Posts
    6

    Intervals of a trinomial...

    I've been struggling on this question for the past hour and a half, and I'm really starting to get frustrated.

    Find the intervals for which the following inequality holds true. Round to 3 decimal places.

    |x^3 - x^2 +x -1| < 3

    Obviously, I added one to both sides of the inequality to get
    -2 < x^3 - x^2 +x -1 < 4
    but I'm completely stumped as to how to simplify the inner trinomial to x. Any help would be greatly appreciated. Thanks!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor Amer's Avatar
    Joined
    May 2009
    From
    Jordan
    Posts
    1,093
    Quote Originally Posted by SpamAndRice View Post
    I've been struggling on this question for the past hour and a half, and I'm really starting to get frustrated.

    Find the intervals for which the following inequality holds true. Round to 3 decimal places.

    |x^3 - x^2 +x -1| < 3

    Obviously, I added one to both sides of the inequality to get
    -2 < x^3 - x^2 +x -1 < 4
    but I'm completely stumped as to how to simplify the inner trinomial to x. Any help would be greatly appreciated. Thanks!
    there is a small error you add 1 to both sides but you did not do that for the middle

    \mid x^3-x^2+x-1 \mid <3

    -3<x^3-x^2+x-1<3 make into two inequalities then find the intersection for the two solutions

    -3<x^3-x^2+x-1.....(1)

    x^3-x^2+x-1<3....(2)


    (1)
    -3<x^3-x^2+x-1

    0<x^3-x^2+x+2

    you need to find the root of the polynomial to study the sign of x^3-x^2+x+2 and take the intervals of x values which make the inequality true but for this there is no exact root there is approximation root you can use intermediate value theorem or you write your question wrong

    and for (2) it is same there is no exact root

    x^3-x^2+x-1<3

    x^3-x^2+x-4<0
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. DE trinomial?
    Posted in the Differential Equations Forum
    Replies: 1
    Last Post: August 30th 2011, 05:35 PM
  2. intervals of increase and the intervals of decrease?
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: February 28th 2010, 09:00 PM
  3. trinomial
    Posted in the Algebra Forum
    Replies: 2
    Last Post: December 8th 2009, 10:09 AM
  4. Little Bit o' Trinomial Help.
    Posted in the Algebra Forum
    Replies: 3
    Last Post: January 19th 2009, 09:04 AM
  5. trinomial
    Posted in the Algebra Forum
    Replies: 3
    Last Post: May 21st 2008, 06:55 PM

Search Tags


/mathhelpforum @mathhelpforum