Limit involving delta-epsilon proof help

In summary, the conversation involves a problem that asks to prove a limit using the delta-epsilon method. The solution involves picking values for epsilon and determining if the first expression is less than epsilon for each value. The individual asks for their solution to be reviewed and confirmed.
  • #1
ZPlayer
35
0
Hi, Everyone,

Problem asks to prove that limit of x^2 * sin^2 (y) / (x^2 + 2* y^2) as (x,y) approach (0,0) is 0 using delta-epsilon method. I think I solved it below. Let me know if I am write or wrong.

Thanks.

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  • #2
I am sorry for the previous post. The solution I have arrived at is actually below.
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  • #3
Something easy you can do is pick some numbers to see if it works. Pick a value for epsilon that's fairly small, such as 0.1. Now pick a point (x, y) that is within delta (= epsilon) of (0,0). Is the value of your first expression less than epsilon?

Now pick a smaller number for epsilon, such as 0.01, and repeat the process as above. This doesn't prove that you have selected the right value of delta, but if you find that the process doesn't give the results you want, then you know you haven't found the right delta.
 
  • #4
I understand your explanation. However, I would appreciate it if you could go over the logic of my solution and answer the question conclusively (i.e. to the best of your knowledge) if my solution is correct or not. Thank you for your time and effort.
 

What is a limit involving delta-epsilon proof?

A limit involving delta-epsilon proof is a mathematical method used to formally prove that a function has a specific limit at a given point. It involves showing that for any desired level of precision (represented by epsilon), there exists a corresponding interval (represented by delta) around the point, within which the function values will always be within the desired precision.

Why is a delta-epsilon proof important?

Delta-epsilon proofs are important because they provide a rigorous and precise method for proving the existence of limits. They also help to establish the continuity and differentiability of functions, which are key concepts in calculus and other areas of mathematics.

What are the key steps in a limit involving delta-epsilon proof?

The key steps in a limit involving delta-epsilon proof are: 1) setting up the desired level of precision (epsilon) and corresponding interval (delta), 2) finding an expression for the distance between the function value and the limit, 3) manipulating the expression to show that it is less than epsilon, and 4) choosing a value for delta that satisfies the desired conditions.

Can you provide an example of a limit involving delta-epsilon proof?

Yes, consider the limit of the function f(x) = x^2 as x approaches 2. We want to prove that the limit is 4. Let epsilon be any positive number, and let delta = min{1, epsilon/5}. Then, for any x satisfying 0 < |x - 2| < delta, we have:|f(x) - 4| = |x^2 - 4| = |x - 2||x + 2| < delta|x + 2| < (epsilon/5)(5) = epsilonThus, the limit is 4 by the definition of a limit involving delta-epsilon proof.

Are there any common mistakes to avoid in a limit involving delta-epsilon proof?

Yes, there are a few common mistakes to avoid when using a delta-epsilon proof. These include: 1) not starting with the desired level of precision (epsilon) and corresponding interval (delta), 2) using incorrect algebraic manipulations, 3) choosing a delta value that is too large or too small, and 4) not clearly stating the assumptions and steps in the proof. It is important to carefully follow the steps and double-check the calculations in a delta-epsilon proof to avoid these mistakes.

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