# stationary points for functions of two variables

• Feb 27th 2008, 06:26 AM
missmath
stationary points for functions of two variables
hi, i have a question concerning stationary points of functions of two variables, i have a problem sheet question - i have done the problem and got the answer but my class mate disagrees with my answer, im trying to find out who is right, its annoying me,

the problem is:

Find and classify the stationary points of the following function:

f(x,y) = 1/3x^3 + 1/3y^3 - x^2 - y^2

I have worked out that there are four stationary points at the following coordinates:

(0,0) Maximum
(2,2) Minimum

My friend thinks there are only two stationary points -the maximum and minimum points from above,

Could anybody help with this problem and settle the score for us as i hate admitting im wrong (Lipssealed)(Rofl)

Any help is appreciated

Thank you

missmath
• Feb 28th 2008, 03:11 AM
mr fantastic
Quote:

Originally Posted by missmath
hi, i have a question concerning stationary points of functions of two variables, i have a problem sheet question - i have done the problem and got the answer but my class mate disagrees with my answer, im trying to find out who is right, its annoying me,

the problem is:

Find and classify the stationary points of the following function:

f(x,y) = 1/3x^3 + 1/3y^3 - x^2 - y^2

I have worked out that there are four stationary points at the following coordinates:

(0,0) Maximum Mr F says: (Yes)
(0,2) Saddle point Mr F says: (Yes)
(2,0) Saddle point Mr F says: (Yes)
(2,2) Minimum Mr F says: (Yes)

My friend thinks there are only two stationary points -the maximum and minimum points from above,

Could anybody help with this problem and settle the score for us as i hate admitting im wrong (Lipssealed)(Rofl)

Any help is appreciated

Thank you

missmath

Tell your friend that Mr Fantastic said s/he is wrong.
• Feb 28th 2008, 05:36 AM
missmath
Yes! I love being right (Rofl) he he

thankyou for taking time to go through it - i really do appreciate it :)

Missmath