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!

Need help with Laplace's Equation

  1. Apr 11, 2012 #1
    1. The problem statement, all variables and given/known data

    Determine whether each of the following functions is a solution of Laplace’s
    equation uxx + uyy = 0.

    x^3 + 3xy^2

    ux=3x^2

    uxx=6x

    uy=6xy^2

    uyy=6x

    6x+6x=12x and is therefore not a solution

    Did I do that right? I'm just learning about this topic and it's a little hard to understand. Can anyone give any advice as to if I approached this correctly?
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Apr 11, 2012 #2
    while your result is correct, your steps are not written down correctly.
     
  4. Apr 11, 2012 #3
    Your derivatives are wrong. The procedure is correct, but your partial derivatives are wrong.

    You have: [tex]f(x,y)=x^3+3xy^2[/tex]
    Then, the derivative with respect to x is:
    [tex]f_x(x,y)=3x^2+3y^2[/tex]

    Everything else is okey. The result you found is fine because when you take the second derivative with respect to x the term involving y vanishes.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Need help with Laplace's Equation
  1. Need help with laplace (Replies: 2)

Loading...