Results 1 to 2 of 2

Math Help - Conic Sections

  1. #1
    Newbie
    Joined
    Aug 2009
    Posts
    18

    Conic Sections

    Hey guys, I need some help on Conic Sections. Specifically how to rewrite equations for hyperbola and elipses in standard form using the completeing the square method.

    Here are two example problems from my math book that i have been having trouble with, i factor them using the completeting the square method but the im not sure how to get them into the standard form.

    9x^2-2y^2+18=0
    I know this one is a hyperbola.

    2x^2+2y^2-10x-18y=1
    This one is a parabola i believe.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,564
    Thanks
    1425
    1.
    9x^2 - 2y^2 + 18 = 0

    9x^2 - 2y^2 = -18

    \frac{-x^2}{2} + \frac{y^2}{9} = 1.

    No need to complete the square.


    2.
    2x^2 + 2y^2 - 10x - 18y = 1

    x^2 - 5x + y^2 - 9y = \frac{1}{2}

    x^2 - 5x + \left(-\frac{5}{2}\right)^2 + y^2 - 9y + \left(-\frac{9}{2}\right)^2 = \frac{1}{2} + \left(-\frac{5}{2}\right)^2 + \left(-\frac{9}{2}\right)^2

    \left(x - \frac{5}{2}\right)^2 + \left(y - \frac{9}{2}\right)^2 = \frac{1}{2} + \frac{25}{4} + \frac{81}{4}

    \left(x - \frac{5}{2}\right)^2 + \left(y - \frac{9}{2}\right)^2 = 27

    \left(x - \frac{5}{2}\right)^2 + \left(y - \frac{9}{2}\right)^2 = \left(3\sqrt{3}\right)^2.

    So this is a circle.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Conic Sections
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: November 4th 2009, 03:15 PM
  2. Conic sections
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: March 3rd 2009, 09:58 AM
  3. conic sections
    Posted in the Calculus Forum
    Replies: 12
    Last Post: February 23rd 2008, 05:22 AM
  4. Conic sections
    Posted in the Pre-Calculus Forum
    Replies: 7
    Last Post: January 31st 2008, 05:09 AM
  5. Conic Sections?
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: November 26th 2007, 05:15 AM

Search Tags


/mathhelpforum @mathhelpforum