Find the solution to this Differential Equation

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Homework Help Overview

The discussion revolves around solving the differential equation ## \frac{dy}{dx} = yLn(y + 1) ##, which involves integrating a function that includes a logarithmic term. Participants are exploring various approaches to find a solution.

Discussion Character

  • Exploratory, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Some participants attempt to separate variables and integrate, expressing difficulties with the integration process. Others suggest using substitutions to simplify the integral, leading to different forms of the equation. There is also a mention of the possibility that an elementary antiderivative may not exist.

Discussion Status

The discussion is ongoing, with participants sharing their attempts and expressing uncertainty about the integration steps. Some have proposed substitutions and transformations, while others are questioning the nature of the integrals involved. No consensus has been reached regarding the solution or the feasibility of finding an elementary form.

Contextual Notes

Participants note that the problem may not have an elementary solution, and there is curiosity about the origin of the problem, suggesting a potential context or constraints that may influence the approach taken.

rodolfomz
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Homework Statement



Find the solution to ## \frac{dy}{dx} = yLn(y + 1) ##

Homework Equations



## \frac{dy}{dx} = yLn(y + 1) ##


The Attempt at a Solution



## \frac{dy}{dx} = yLn(y + 1)##

## \frac{dy}{yLn(y + 1)} = dx ##

but then i can't integrate, any help?
 
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rodolfomz said:

Homework Statement



Find the solution to ## \frac{dy}{dx} = yLn(y + 1) ##

Homework Equations



## \frac{dy}{dx} = yLn(y + 1) ##


The Attempt at a Solution



## \frac{dy}{dx} = yLn(y + 1)##

## \frac{dy}{yLn(y + 1)} = dx ##

but then i can't integrate, any help?
Using a substitution (u = ln(y + 1)) I was able to get to this integral:
$$\int \frac{du}{u} + \int \frac{du}{u(e^u + 1)}$$
The first integral is very simple. The second might be amenable to another substitution, but I didn't go any further.
 
thats what I have

## ∫\frac {dy}{y*ln(y+1)}=∫dx ##
changing variables
## u=ln(y+1) ; du=\frac{dy}{y+1} ##

##\int \frac{e^u*du}{(u)*(e^u -1)} = x ##
which is the same as

##\int \frac{du}{u}*\frac{e^u}{e^u-1} = x##

and then resolving by parts dv= du/u and u=e^u/e^u-1

##\frac{e^u}{e^u-1}+\int \frac{ln(u)*e^udu)}{(e^u-1)^2}##

im stuck here
 
rodolfomz said:

Homework Statement



Find the solution to ## \frac{dy}{dx} = yLn(y + 1) ##

Homework Equations



## \frac{dy}{dx} = yLn(y + 1) ##


The Attempt at a Solution



## \frac{dy}{dx} = yLn(y + 1)##

## \frac{dy}{yLn(y + 1)} = dx ##

but then i can't integrate, any help?

I doubt there is an elementary antiderivative. Where did this problem come from?
 

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