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!

Partial Derivatives

  1. May 13, 2009 #1
    1. The problem statement, all variables and given/known data
    Find point closest to origin xy2z3 = 2



    2. Relevant equations



    3. The attempt at a solution

    note, k = lagrange multiplier

    grad f = 2xi + 2yj + 2zk, k grad f = k(y2z3i + 2xyz3j + 3z2xy2k)

    k = 2xy-2z-3 = x-1z-3 = (2/3)z-1x-1y-2

    y = [tex]\sqrt{2x^2}[/tex]

    x = [tex]\sqrt{(y^2)/2}[/tex]

    z = [tex]\sqrt{(3y^2)/2}[/tex]

    Plug x and z into the original

    ([tex]\sqrt{(y^2)/2}[/tex])(y2)([tex]\sqrt{(3y^2)/2}[/tex])3 = 2

    I tried to simplify that, first i squared both sides

    (y2/2)(y4)((27y6)/8) = 4

    (27/16)y12 = 4

    y = (4(16/27))1/12

    y = (64/27)1/12 = 1.074569932

    anyone agree, diagree
     
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted



Similar Discussions: Partial Derivatives
  1. The partial derivative (Replies: 2)

  2. Partial derivatives (Replies: 11)

  3. Partial Derivatives (Replies: 4)

  4. Partial derivative (Replies: 7)

  5. Partial derivative (Replies: 4)

Loading...