My Math Forum  

Go Back   My Math Forum > College Math Forum > Calculus

Calculus Calculus Math Forum

LinkBack Thread Tools Display Modes
May 11th, 2014, 02:50 AM   #1
Joined: Apr 2014
From: australia

Posts: 68
Thanks: 32

critical points of function

hi all,

for function;
f(x,y)= ln(x+y) + x^2 - y - 64

I'm trying to find all critical points & determine whether there is a local max, local min, saddle point or none of these at each critical point.

harley05 is offline  
May 11th, 2014, 08:11 AM   #2
Senior Member
fysmat's Avatar
Joined: Dec 2013
From: some subspace

Posts: 212
Thanks: 72

Math Focus: real analysis, vector analysis, numerical analysis, discrete mathematics
Critical points are points where all the (partial)derivatives are equal to 0, and points where at least one of the derivatives is not defined.

The discriminant, to determine whether the point is maxima, minima or saddle point, is:

$\displaystyle \Delta = f_{xx}\,f_{yy} - f_{xy}^2$.

At which part of this you have difficulties?
fysmat is offline  

  My Math Forum > College Math Forum > Calculus

critical, function, points

Thread Tools
Display Modes

Similar Threads
Thread Thread Starter Forum Replies Last Post
Critical Points of a Rational Function Tzad Calculus 8 November 7th, 2013 07:55 PM
critical points of a function dean Calculus 6 September 16th, 2012 07:41 PM
Critical points and min/max again. Timk Calculus 3 November 29th, 2011 10:59 AM
critical points of given function maximus101 Calculus 3 March 11th, 2011 06:51 PM
Critical points SSmokinCamaro Calculus 2 April 3rd, 2009 07:04 PM

Copyright © 2019 My Math Forum. All rights reserved.