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 and power rule

  1. Feb 28, 2012 #1
    1. The problem statement, all variables and given/known data

    ∂f/∂x (xy -1)2 = 2y(xy-1)


    3. The attempt at a solution


    I would think the answer would be

    2(xy-1)

    I don't understand where the y comes from in 2y
     
  2. jcsd
  3. Feb 28, 2012 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    It comes from the chain rule. Look it up!
     
  4. Feb 28, 2012 #3
    It looks like they're using u substitution

    (u)2 = 2u

    u = xy - 1
    du or ∂f/∂x(not sure about the notation) = y

    2u * y = 2y(u), insert u = 2y(xy-1)
     
  5. Feb 28, 2012 #4
    i solved the problem before I saw dick's reply
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Partial derivatives and power rule
Loading...