Results 1 to 3 of 3

Math Help - quadratic equation problem

  1. #1
    Member
    Joined
    Oct 2009
    Posts
    201

    quadratic equation problem

    Given that one of the root of the quadratic equation 2x(4x-9)=4-3p is half the other root.find:

    a)value of p

    b) root of the quadratic equation..


    anyone sir...please help!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    Joined
    Jun 2009
    Posts
    806
    Thanks
    4
    Quote Originally Posted by mastermin346 View Post
    Given that one of the root of the quadratic equation 2x(4x-9)=4-3p is half the other root.find:

    a)value of p

    b) root of the quadratic equation..


    anyone sir...please help!
    If α and β are the roots of a quadratic equation ax^2 + bx + c = 0, then
    the product of the roots α*β = c/a. and sum of the roots (α + β) = -(b/a)
    Using sum of the roots equation, find α. Using the product of roots equation, find p.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor
    Joined
    Dec 2009
    Posts
    3,120
    Thanks
    1
    Quote Originally Posted by mastermin346 View Post
    Given that one of the root of the quadratic equation 2x(4x-9)=4-3p is half the other root.find:

    a)value of p

    b) root of the quadratic equation..


    anyone sir...please help!
    Hi mastermin346,

    sa-ri-ga-ma's method is a fast way...

    the long way to do it is

    the equation in ax^2+bx+c form is 8x^2-18x+(3p-4)=0

    One root is \frac{18+\sqrt{18^2-32(3p-4)}}{16}

    The other root is \frac{18-\sqrt{18^2-32(3p-4)}}{16}

    The larger root must be the first one if the roots are real.

    Then twice the second root is the first.

    2\left(18-\sqrt{324-32(3p-4)}\right)=18+\sqrt{324-32(3p-4)}

    18=3\sqrt{324-32(3p-4)}

    \sqrt{324-32(3p-4)}=6

    324-32(3p-4)=36

    32(3p-4)=324-36=288

    4(3p-4)=36

    3p-4=9

    p=\frac{13}{3}

    The equation is

    8x^2-18x+13-4=0

    8x^2-18x+9=0

    Either find the roots of this or substitute "p" into

    \frac{18\pm\sqrt{324-32(9)}}{16}
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Quadratic equation problem
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: September 20th 2010, 09:06 PM
  2. quadratic equation problem
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: May 28th 2010, 02:37 PM
  3. quadratic equation problem
    Posted in the Algebra Forum
    Replies: 5
    Last Post: May 24th 2010, 10:28 AM
  4. quadratic equation problem 3
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: October 6th 2009, 11:56 AM
  5. Quadratic equation problem..
    Posted in the Algebra Forum
    Replies: 2
    Last Post: January 29th 2008, 01:21 PM

Search Tags


/mathhelpforum @mathhelpforum