Find an f that satisfies these statements - Deltas and Epsilons

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In summary, the problem is asking for a function f that satisfies the statement: for every positive epsilon, there exists a positive delta and a value x that is within delta units of a and also satisfies the condition that f(x) is within epsilon units of L. The student is asking for a hint on how to find such a function.
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Numnum
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Homework Statement



Find an f that satisfies this statement:
[tex]
\lim_{x\rightarrow a} f(x)≠L
[/tex]

[tex]∀ε>0 ∃δ>0∃ x:0<|x-a|<δ AND |f(x)-L|<ε[/tex]

Homework Equations

The Attempt at a Solution



I'd just like a small hint on how I would go about finding a function. How can there be a delta for every epsilon and the rest of the statement is fulfilled, but there is no limit? The notation's just a tad confusing.
 
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  • #2
Numnum said:

Homework Statement



Find an f that satisfies this statement:
[tex]
\lim_{x\rightarrow a} f(x)≠L
[/tex]

[tex]∀ε>0 ∃δ>0∃ x:0<|x-a|<δ AND |f(x)-L|<ε[/tex]

Homework Equations




The Attempt at a Solution



I'd just like a small hint on how I would go about finding a function. How can there be a delta for every epsilon and the rest of the statement is fulfilled, but there is no limit? The notation's just a tad confusing.

You aren't quantifying this right. There just has to be one epsilon without any corresponding delta. lim x->0 x isn't equal to 1. Prove it.
 

FAQ: Find an f that satisfies these statements - Deltas and Epsilons

What is the purpose of finding an f that satisfies Deltas and Epsilons?

The purpose of finding an f that satisfies Deltas and Epsilons is to solve for a function that meets certain criteria or conditions, as defined by delta and epsilon values. This is often used in mathematical proofs and in calculus to show that a limit exists or to approximate a value.

What are Deltas and Epsilons in this context?

In this context, Deltas and Epsilons refer to values that represent a small change or difference in the input and output of a function. Delta represents a change in the input, while Epsilon represents a change in the output. These values are used to define the desired characteristics of the function being solved for.

How do you find an f that satisfies Deltas and Epsilons?

To find an f that satisfies Deltas and Epsilons, you must first define the desired characteristics of the function using delta and epsilon values. Then, using mathematical techniques such as limit laws and algebraic manipulation, you can solve for the function that meets those conditions.

What are some common applications of finding an f that satisfies Deltas and Epsilons?

Finding an f that satisfies Deltas and Epsilons is commonly used in mathematical proofs, such as epsilon-delta proofs in calculus. It is also used in numerical analysis to approximate solutions to equations and in optimization problems to find the maximum or minimum value of a function.

Are there any limitations to using Deltas and Epsilons to find an f?

While Deltas and Epsilons can be useful in solving for a desired function, there are limitations to this method. It may not always be possible to find a single function that satisfies all the defined conditions, and in some cases, the function may not be unique. Additionally, this method may not be applicable to all types of functions, such as discontinuous or non-differentiable functions.

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