Finding Critical Points

[KEYWEST17]

Find the critical points for the function and classify each as a local maximum, local minimum, saddle point, or none of these

I got the following values:

Fx= 6x-6y
Fy=-6x+10-8
Fxx=6
Fyy=

 

[tkhunny]

Try Fy again.

 

[Deleted member 4993]

Find the critical points for the function and classify each as a local maximum, local minimum, saddle point, or none of these

I got the following values:

Fx= 6x-6y
Fy=-6x+10-8
Fxx=6
Fyy=

Good - now tell us the conditions for local maximum, local minimum, saddle point,

 

[KEYWEST17]

Thats what I am unsure of.

I know if x >0 its a local min

if x<0 it is a local max

if x=0 it is inconclusive

 

[tkhunny]

Did you try Fy again? Trust me on this.

 

[KEYWEST17]

No I am not sure how to get it because the numbers look ugly.

 

[tkhunny]

You were close on your original attempt. Fix it. You are sure where to begin. You just did a few minutes ago.

 

[KEYWEST17]

Fyy=10

 

[tkhunny]

So, we're just never going to fix Fy, but magaically we get Fyy? Please be complete and careful.

Okay, now classify things.

1) Are the first partials simultaneously zero?
2) If so, where nd what do the second aprtials tell us about such locations?

 

[KEYWEST17]

I' not following what your saying

 

[tkhunny]

I'm starting to think you are in the wrong class.

Please find any critical points of this function: f(x) = 3x^3 - 5
Describe the nature of any you find.

 

[KEYWEST17]

x^3-(5/3)=0

 

[tkhunny]

RBGTHGANH