1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

More Implicit Differentiation Help

  1. Jul 12, 2012 #1
    1. The problem statement, all variables and given/known data
    Find an equation of the tangent line to x^3 + y^3 - 6xy = 0 at the point ((4/3), (8/3))

    2. Relevant equations
    I got y = -(8/5)x + (24/5). Is this correct?

    3. The attempt at a solution
    Lots of algebra involved. Sorry. but I'd rather not type it. I take the derivative of each term and eventually get:

    [-3x^2 - 6y] / [3y^2 - 6x].

    This simplifies to:

    [x^2 + 2y] / [2x - y^2].

    I substitute the stuff in appropriately, I get m = -(8 / 5).

    Then I do:

    y - (8/3) = -(8 / 5)(x - (4/3)).

    I ask because Wolfram Alpha disagrees with me:
  2. jcsd
  3. Jul 12, 2012 #2


    User Avatar
    Homework Helper

    You're off by a sign, it should be

  4. Jul 12, 2012 #3
    I see. I didn't distribute a "- 6" to a "+ y" properly. Thanks.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: More Implicit Differentiation Help