Results 1 to 4 of 4

Math Help - Find the focus and directrix of the parabola

  1. #1
    htk
    htk is offline
    Newbie
    Joined
    Sep 2009
    Posts
    2

    Find the focus and directrix of the parabola

    Find the focus, directrix and axis of the parabola with equation x= 2y^2+3?
    x-3= 2y^2

    x-3 = y^2 -------------> Is it how you solve it?

    Thank you for helping me!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    earboth's Avatar
    Joined
    Jan 2006
    From
    Germany
    Posts
    5,804
    Thanks
    115
    Quote Originally Posted by htk View Post
    Find the focus, directrix and axis of the parabola with equation x= 2y^2+3?
    x-3= 2y^2

    x-3 = y^2 -------------> Is it how you solve it?

    Thank you for helping me!
    1. This is a parabola opening to the right. The general equation of such a parabola is:

    (y-h)^2=4p(x-k) where V(k, h) is the vertex, F(k+p, h) is the focus and d: x = k-p is the equation of the directrix.

    2. Transform the given equation into the general form:

    x=  2y^2+3~\implies~(y-0)^2=\frac12(x-3)~\implies~(y-0)^2=4 \cdot \frac18(x-3)

    3. Determine V, F and d.
    Last edited by earboth; June 9th 2010 at 01:55 AM. Reason: typo detected
    Follow Math Help Forum on Facebook and Google+

  3. #3
    htk
    htk is offline
    Newbie
    Joined
    Sep 2009
    Posts
    2
    So, V (3,0) F=(25/8, 0) D x= 23/8 Are these correct? Thanks again!

    4p= 1/2
    p= 1/8
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Super Member
    earboth's Avatar
    Joined
    Jan 2006
    From
    Germany
    Posts
    5,804
    Thanks
    115
    Quote Originally Posted by htk View Post
    So, V (3,0) F=(25/8, 0) D x= 23/8 Are these correct? Thanks again!

    4p= 1/2
    p= 1/8
    Perfect!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Parabola and Directrix and Focus.
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: November 15th 2010, 11:19 PM
  2. Parabola: Vertex, Focus, Directrix
    Posted in the Algebra Forum
    Replies: 1
    Last Post: June 30th 2010, 04:48 AM
  3. Replies: 2
    Last Post: April 9th 2010, 02:28 AM
  4. Replies: 3
    Last Post: March 22nd 2010, 12:49 PM
  5. vertex, focus, and directrix of parabola
    Posted in the Pre-Calculus Forum
    Replies: 0
    Last Post: May 2nd 2009, 05:07 PM

Search Tags


/mathhelpforum @mathhelpforum