1. Not finding help here? Sign up for a free 30min 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!

Lagrange Mulltipliers

  1. Oct 26, 2009 #1
    1. The problem statement, all variables and given/known data

    Find max/min using L.M of the function :

    F(x,y) = x^2 + y^2 ; xy = 1

    let G(x,y) = xy - 1

    F_x = 2x
    F_y = 2y
    G_x = y
    G_y = x

    F_x = L*G_x
    F_y = L*G_y
    G(x,y) = 1


    1) 2x = L * y
    2) 2y = L * x
    3 ) xy = 1

    Now I need to solve those equations.

    so x = LY/2 ; y = LX/2

    Then if I plug it in I get X = L^2/4 and similar for Y
    Not sure how to approach that step
     
  2. jcsd
  3. Oct 26, 2009 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    x=Ly/2 and y=Lx/2 doesn't tell you x=L^2/4. Try that again.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Lagrange Mulltipliers
  1. Lagrange with integral (Replies: 2)

  2. Lagrange Multipliers (Replies: 8)

  3. Lagrange Multipliers (Replies: 8)

  4. Lagrange's Identity (Replies: 7)

Loading...