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Partial Derivative help

  1. Mar 5, 2012 #1
    1. The problem statement, all variables and given/known data

    w = 2xy + 4yz + 5xz
    x = st
    y = 3^(st)
    z = t^2

    s=5
    t=1

    2. Relevant equations

    Chain rule: xy = x*y' + y*x'

    3. The attempt at a solution

    w = 2stest + 4test + 5st3

    (partial derivatives) dw/dt = 2s2test + 2sest + 4tsst + 4est + 15st2

    (partial derivatives) dw/dt (5,1) = 2(5)2e5 + 2*5e5 + 20e5 + 4e5 + 75

    = 84e5+75

    This is not correct. What did I mess up on? Thanks!
     
    Last edited: Mar 5, 2012
  2. jcsd
  3. Mar 5, 2012 #2
    When you said, y = 3^(st), did you mean y = e^(st)?
     
  4. Mar 5, 2012 #3
    Yes I did mean that, but I actually figured out what I did wrong. I subbed in a y as t and not t^2.
     
  5. Mar 5, 2012 #4
    Your 4yz term is not correct.

    EDIT: Yep, beat me to it.
     
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