Existence-Uniqueness problems.

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Discussion Overview

The discussion revolves around the Existence-Uniqueness theorem in the context of initial value problems (IVPs) involving differential equations. Participants seek to determine whether the theorem guarantees a unique solution for specific equations, while also addressing the integration of a particular function.

Discussion Character

  • Homework-related
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant requests help with the integral of 1/ln(y) and poses two IVPs to analyze using the Existence-Uniqueness theorem.
  • Another participant questions the relevance of the integral and asks for clarification on what the Existence-Uniqueness theorem entails.
  • A participant suggests that solving the differential equation is necessary to find a unique solution but expresses uncertainty about the integration process.
  • Another reply emphasizes that solving the equation is not required to determine the uniqueness of the solution according to the theorem and prompts for the theorem's hypotheses.
  • There is a suggestion that even if the integral could be expressed in elementary functions, it may not address the original question posed.

Areas of Agreement / Disagreement

Participants appear to have differing views on the necessity of solving the differential equation to apply the Existence-Uniqueness theorem, indicating a lack of consensus on the approach to the problem.

Contextual Notes

There is uncertainty regarding the integration of the function 1/ln(y) and the specific conditions under which the Existence-Uniqueness theorem applies to the given IVPs.

Who May Find This Useful

This discussion may be of interest to students and educators involved in differential equations, particularly those exploring the implications of the Existence-Uniqueness theorem in solving initial value problems.

hermtm2
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Hello.

I can't do Integral(1/ln(y)dy). Can you guys help me out?

This is the original problem.

In each of these IVPs, determine whether or not the Existence-Uniqueness Theorom guarantees a unique solution.

1. dy/dx = ln(y), y(0)=0
2. dy/dx = ln(y), y(1)=1

Thanks.
 
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hermtm2 said:
Hello.

I can't do Integral(1/ln(y)dy).
Why does that matter? What is the "Existence-Uniqueness theorem"?

(I assume by "do" you mean "rewrite as an algebraic combination of elementary functions"?)
 
Solve for differential equation to find a unique solution. In order to solve the equation, I have to integrate it but I don't know how to do it.
 
hermtm2 said:
In order to solve the equation, I have to integrate it but I don't know how to do it.
Then find another way to answer the question you were asked!

What is the "Existence-Uniqueness theorem"?
 
P.S. even if you could rewrite this integral in terms of elementary functions, I don't think that would answer the question you were asked...
 
Hurkyl's point is that you do NOT need to solve the equation to "determine whether or not the Existence-Uniqueness Theorom guarantees a unique solution."

Answer his first question: What is the "Existence-Uniqueness Theorem"? What are it hypotheses.
 

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