Finding critical points from level curves

In summary, the conversation is about finding the critical points and classifying them as local max, min, or saddle. The solution involves checking the z-values of the level curves near the critical points to determine if they are increasing or decreasing. It is important to pay attention to the z-values as they indicate whether the point is a local max or min.
  • #1
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Homework Statement



I was given the following level curve (image is attached). I need to find the critical points and classify them (local max, min, saddle).


The Attempt at a Solution



I can find the points easily enough. Saddle at (-1,0), and then locals at each of the three circles. However, I cannot figure out if they are local max or mins. How can I tell from the surface if it is a max or a min? To me it looks as though it could go either way.

Thanks,

Chris
 

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  • #2
Look at the z-values of the level curves close to the points. Are they increasing or decreasing as you move toward the critical point?
 
  • #3
Ah got it...I knew it was simple, just didn't catch that those were the Z values. Thanks
 

Related to Finding critical points from level curves

1. What are critical points?

Critical points are points on a graph where the derivative of a function is equal to zero. These points are important because they indicate where the slope of the function is changing, which can give insights into the behavior of the function.

2. How can I find critical points from level curves?

To find critical points from level curves, you can use the contour lines on the graph to identify regions where the function is increasing or decreasing. Then, you can use the derivative of the function to determine where the slope is equal to zero, thus identifying the critical points.

3. Can critical points be found using any type of function?

Yes, critical points can be found for any type of function, including polynomial, trigonometric, exponential, and logarithmic functions. The method for finding them may vary slightly depending on the type of function, but the concept remains the same.

4. Are all critical points considered to be local extrema?

No, not all critical points are considered to be local extrema. Some critical points may be inflection points, where the slope of the function changes from increasing to decreasing or vice versa. Only critical points that are also local extrema, such as maxima or minima, are considered as such.

5. How can critical points be used to determine the behavior of a function?

Critical points can be used to determine the behavior of a function by analyzing the slope of the function at and around the critical points. For example, if the slope is increasing towards a critical point, it may be an indication of a minimum value. Additionally, critical points can also be used to find the overall shape and characteristics of a function, such as concavity and inflection points.

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