Posted by Lucy on Tuesday, February 28, 2012 at 12:43am.
Find and classify all local min and maxima and saddle points of the function f(x,y)=/3yx^23xy^2+36xy
I know there are 3 saddle points and one maxima.
This is what I got:
D=FxxFyy(Fxy)^2
= 36xy36(x+y6)^2
But how do i solve for zero?? Im lost on this one. Please help me figure out these points??

Calculus Find max and min and saddle  MathMate, Tuesday, February 28, 2012 at 7:37am
First you'd have to find the local maxima/minima. If you have obtained the (four) points, then you can use the second derivative test to determine if each one is a maximum/minimum or saddle point.
Have you found the critical points?
(Unfortunately the definition of f(x,y) above does not seem to be complete.)
Note:singular: maximum, plural: maxima. 
Calculus Find max and min and saddle  George, Wednesday, December 2, 2015 at 7:32am
Lucy
I think you are wrong,what I got is much that I can't type ,mayb some social network or video call .