Results 1 to 3 of 3

Math Help - Solving Inequalities

  1. #1
    Member
    Joined
    Nov 2007
    Posts
    232

    Solving Inequalities

    How would you solve the following inequality algebraically?

    0.5(x + 2)^2 (x - 4) > 2x + 3

    Is it. . .

    0.5(x + 2)^2 (x - 4) - 2x + 3 > 0

    And use interval charts?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Bar0n janvdl's Avatar
    Joined
    Apr 2007
    From
    South Africa
    Posts
    1,630
    Thanks
    6
    Quote Originally Posted by Macleef View Post
    How would you solve the following inequality algebraically?

    0.5(x + 2)^2 (x - 4) > 2x + 3

    Is it. . .

    0.5(x + 2)^2 (x - 4) - 2x + 3 > 0

    And use interval charts?
    Multiply by 2 throughout the equation

     (x + 2)^2 (x - 4) > 4x + 6

     (x^2 + 4x + 4) (x - 4) > 4x + 6

     x^3 - 4x^2 + 4x^2 - 16x + 4x - 16 -4x - 6 > 0

     x^3 - 16x - 22 > 0

    x = -2,9 ; -1,66 ; 4,5
    Last edited by janvdl; January 13th 2008 at 08:57 PM. Reason: Thanks for the spot mr_fantastic
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by janvdl View Post
    Multiply by 2 throughout the equation Mr F explains: To make life easier.

     (x + 2)^2 (x - 4) > 4x + 6 Mr F corrects:

     (x^2 + 4x + 4) (x - 4) > 4x + 6

     x^3 - 4x^2 + 4x^2 - 16x + 4x - 16 - 4x - 6 > 0

     x^3 - 16x - 22 > 0

    The roots of this equation still aren't exactly nice ones to work with .....
    Alterations and paint work by Mr F.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. A little help solving inequalities
    Posted in the Calculus Forum
    Replies: 1
    Last Post: November 4th 2009, 06:32 PM
  2. Solving Inequalities
    Posted in the Algebra Forum
    Replies: 2
    Last Post: October 8th 2009, 04:57 AM
  3. Solving Inequalities
    Posted in the Algebra Forum
    Replies: 1
    Last Post: February 11th 2008, 01:01 PM
  4. Solving Inequalities
    Posted in the Algebra Forum
    Replies: 1
    Last Post: February 2nd 2008, 02:00 AM
  5. Solving inequalities
    Posted in the Algebra Forum
    Replies: 4
    Last Post: February 17th 2007, 04:12 PM

Search Tags


/mathhelpforum @mathhelpforum