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!

Homework Help: Lagrange Multipliers (Multivariable Calc)

  1. May 6, 2007 #1
    1. The problem statement, all variables and given/known data
    Find the maximum x1, x2, x3, in the ellipsoid
    x1^2/a^2 + x2^2/b^2 + x3^2/c^2 < 1 and all the places where this value is attained.

    2. Relevant equations

    3. The attempt at a solution
    My teacher said to use the lagrange multiplier.
    So far, I have that we are maximizing x1, x2, and x3 such that x1^2/a^2 + x2^2/b^2 + x3^2/c^2 < 1.

    In any case, I figured that the constraint would be the equation for the ellipsoid, but I haven't a clue what exactly we would be maximizing for.
    I would assume the maximum of x1,x2, and x3 would simply be the norm of the vector created by the three values.
    Last edited: May 7, 2007
  2. jcsd
  3. May 7, 2007 #2


    User Avatar
    Homework Helper
    Gold Member

    You need to show your work before you get help. What have you done with this problem?
  4. May 7, 2007 #3
    yeah I added what I did, but I feel like I'm going in the wrong direction.
  5. May 7, 2007 #4


    User Avatar
    Science Advisor

    I wouldn't. I accept exactly what was said here: that you are asked to find three separate values: the maximum value of x, the maximum value of y, and the maximum value of z- and you don't need "Lagrange multiplier", you can read them off the equation of the ellipsoid. If you think your teacher means anything else, you should ask him or her.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook