Find the solution to this Differential Equation

In summary, the problem asks to find the solution to the differential equation ## \frac{dy}{dx} = yLn(y + 1) ##. After some attempts at solving, it is determined that there is likely no elementary antiderivative for this equation.
  • #1
rodolfomz
2
0

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?
 
Physics news on Phys.org
  • #2
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.
 
  • #3
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
 
  • #4
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?
 

1. What is a differential equation?

A differential equation is a mathematical equation that describes the relationship between a function and its derivatives. It often appears in the form of an equation involving the rates of change of a variable.

2. Why is solving differential equations important?

Differential equations are used to model various real-world phenomena in fields such as physics, engineering, economics, and biology. Solving these equations allows us to understand and predict the behavior of complex systems and make informed decisions.

3. What methods are used to solve differential equations?

There are several methods for solving differential equations, including separation of variables, substitution, integrating factors, and using power series. The specific method used depends on the type of differential equation and its properties.

4. Can all differential equations be solved analytically?

No, not all differential equations have analytical solutions. In some cases, numerical methods must be used to approximate the solution. However, many common types of differential equations, such as linear and separable equations, can be solved analytically.

5. How do I know if I have found the correct solution to a differential equation?

To verify the solution to a differential equation, you can plug it back into the original equation and see if it satisfies the equation. Additionally, you can check for any initial conditions or boundary conditions given in the problem and make sure the solution satisfies them as well.

Similar threads

  • Calculus and Beyond Homework Help
Replies
19
Views
776
  • Calculus and Beyond Homework Help
Replies
6
Views
760
  • Calculus and Beyond Homework Help
Replies
2
Views
736
  • Calculus and Beyond Homework Help
Replies
13
Views
276
  • Calculus and Beyond Homework Help
Replies
1
Views
829
  • Calculus and Beyond Homework Help
Replies
21
Views
842
  • Calculus and Beyond Homework Help
Replies
24
Views
1K
  • Calculus and Beyond Homework Help
Replies
3
Views
905
  • Calculus and Beyond Homework Help
Replies
8
Views
763
  • Calculus and Beyond Homework Help
Replies
12
Views
1K
Back
Top