Results 1 to 2 of 2

Math Help - Implicit Differentiation

  1. #1
    Newbie
    Joined
    Apr 2009
    Posts
    13
    x^2-xy-4y^2=0
    Find: (dy)/(dx)

    Thanks in advance!

    I got this answer:
     <br />
(dy)/(dx)=(y+10x)/(x+8y)<br />
    and i just want to make sure I did it right...
    Last edited by mr fantastic; April 23rd 2009 at 06:19 PM. Reason: Merged posts
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Member
    Joined
    Apr 2009
    Posts
    166
    Edit: Oh you just had to get banned. =p

    x^2 - xy - 4y^2 = 0

    (2x) - (y + xy') - (8yy') = 0

    2x - y - xy' - 8yy' = 0

    (xy' + 8yy') = (2x - y)

    y'(x + 8y) = (2x - y)

    y' = \frac{2x - y}{x + 8y}

    Easier way to do it when you've got it in that form: -(d/dx)/(d/dy)

    d/dx = 2x - y
    d/dy = -x - 8y

    \frac{-(d/dx)}{(d/dy)} = \frac{-(2x - y)}{-x - 8y} = \frac{2x - y}{x + 8y}
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 2
    Last Post: July 26th 2010, 05:24 PM
  2. implicit differentiation
    Posted in the Calculus Forum
    Replies: 3
    Last Post: May 1st 2010, 07:42 AM
  3. Implicit Differentiation
    Posted in the Calculus Forum
    Replies: 4
    Last Post: April 28th 2010, 03:19 PM
  4. Implicit differentiation
    Posted in the Calculus Forum
    Replies: 3
    Last Post: April 26th 2010, 05:41 PM
  5. Implicit Differentiation
    Posted in the Calculus Forum
    Replies: 3
    Last Post: March 25th 2008, 07:33 PM

Search Tags


/mathhelpforum @mathhelpforum