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!

Help! exam tomorrow and stuck on this proof

  1. May 25, 2009 #1
    i have a math method exam tomorrow, and im really stuck on this proof, im not sure how they have manipulated the 2nd bracket to get the other version of this equation. any help would be much appreciated.

    To establish just what constitutes sufficient conditions we first note that, since
    f is a function of two variables and ∂f/∂x = ∂f/∂y = 0, a Taylor expansion of
    the type (5.18) about the stationary point yields
    f(x, y) − f(x0, y0) ≈1/2! [(Δx)2fxx + 2ΔxΔyfxy + (Δy)2fyy]

    where Δx = x − x0 and Δy = y − y0 and where the partial derivatives have been
    written in more compact notation. Rearranging the contents of the bracket as
    the weighted sum of two squares, we find
    f(x, y) − f(x0, y0) ≈1/2![fxx(Δx + fxyΔy/fxx)^2 +(Δy)^2(fyy −f^2xy/fxx]

  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: Help! exam tomorrow and stuck on this proof
  1. Help with the proof (Replies: 10)

  2. Proof help? (Replies: 4)