Critical Points of f(x,y)= x^{3} - 6xy + y^{3}

In summary, the conversation is about finding and classifying all critical points of a mathematical function. The person shares their attempt at solving the problem and asks for feedback. Another person points out a mistake and suggests an alternative approach. They also mention using Wolfram Alpha to check the work and note that one of the answers is correct but the others are wrong.
  • #1
jegues
1,097
3

Homework Statement



Find and classify all critical points of,

[tex]f(x,y)= x^{3} - 6xy + y^{3}[/tex]

Homework Equations





The Attempt at a Solution



See figure attached for my attempt at the solving all the critical points. I'm getting some weird numbers so I want to make sure I did this part correct before I start classifying them.

Does anyone see any problems?

Thanks again!
 

Attachments

  • 09Q7.jpg
    09Q7.jpg
    27.8 KB · Views: 431
Physics news on Phys.org
  • #2
hi jegues! :smile:

in line 6, your 1/8 should be 1/4 :redface:

(btw, it would be a lot easier if you divided everything by 3 first)
 
  • #3
You can quickly check your work using wolfram alpha... and according to it, (0,0) is one but your other answers are wrong.
 

FAQ: Critical Points of f(x,y)= x^{3} - 6xy + y^{3}

What is the definition of a critical point?

A critical point is a point on a graph where the derivative is equal to zero, or where the derivative does not exist. It is also known as a stationary point, as the slope of the graph is horizontal at this point.

Why is finding critical points important?

Finding critical points is important because it helps us identify the maximum and minimum values of a function. These points can also provide information about the behavior of a function and can be used to optimize a system.

How do you find the critical points of a function?

To find the critical points of a function, you need to take the derivative of the function and set it equal to zero. Then, solve for the variable to find the x-values of the critical points. These x-values can then be substituted back into the original function to find the corresponding y-values.

What is the difference between relative and absolute critical points?

Relative critical points are points where the derivative is equal to zero, while absolute critical points are points where the derivative does not exist. Absolute critical points are also known as singular points, and they can be found by setting the derivative equal to undefined values, such as infinity or negative infinity.

How do you determine if a critical point is a maximum, minimum, or point of inflection?

To determine the type of critical point, you need to analyze the behavior of the function on either side of the critical point. If the function is increasing before the critical point and decreasing after, it is a maximum point. If the function is decreasing before the critical point and increasing after, it is a minimum point. If the function is increasing or decreasing on both sides of the critical point, it is a point of inflection.

Similar threads

Replies
4
Views
730
Replies
4
Views
2K
Replies
6
Views
1K
Replies
5
Views
2K
Replies
11
Views
2K
Back
Top