1. Not finding help here? Sign up for a free 30min 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!

True of false about partial derivative

  1. Oct 23, 2009 #1
    1. The problem statement, all variables and given/known data
    if (2,1) is a critical point of f and fxx(2,1)fyy(2,1) < (fxy(2,1))^2
    then f has a saddle point at (2,1)


    2. Relevant equations



    3. The attempt at a solution
    i think its right
    but it turns out to be wrong
    can someone tell me why?
     
  2. jcsd
  3. Oct 23, 2009 #2

    lanedance

    User Avatar
    Homework Helper

    wouldn't it need fx(2,1) = fy(2,1) = 0 as well?
     
  4. Oct 23, 2009 #3
    could you please explain it a little bit more?
     
  5. Oct 23, 2009 #4

    lanedance

    User Avatar
    Homework Helper

    ok now i see it is already a critical point, i would agree with you then
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: True of false about partial derivative
  1. Calc vertice problem (Replies: 1)

Loading...