Solve homogeneous first order PDE's

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Homework Help Overview

The discussion revolves around solving a homogeneous first-order partial differential equation (PDE) of the form u_x + u_y + u = e^{x+2y} with an initial condition y(x,0) = 0. Participants express uncertainty about the appropriate methods to apply in this context.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Some participants suggest trying to separate variables as a potential method, while others express confusion about this approach. There are attempts to use the method of characteristics, but one participant notes difficulties with this method. Questions arise regarding the validity of assuming a solution can be expressed as a product of functions of x and y.

Discussion Status

The discussion is ongoing, with participants exploring different methods and questioning the assumptions underlying their approaches. There is no clear consensus on the best way to proceed, but several lines of reasoning are being examined.

Contextual Notes

Participants are grappling with the initial condition and the nature of the non-homogeneous term in the PDE, which complicates their attempts to apply standard techniques for homogeneous equations.

Dragonfall
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[tex]u_x+u_y+u=e^{x+2y}, y(x,0)=0[/tex]

I have no idea how to do this. We were only taught how to solve homogeneous first order PDE's.
 
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What do you mean?
 
I am getting nowhere with this. I tried using the method of characteristics, but it doesn't work out.
 
Dragonfall said:
What do you mean?
Write [tex]u(x,y)=X(x)Y(y)[/tex], plug this into you equation and...

Note also: [tex]e^{x+2y}=e^xe^{2y}[/tex]
 
How do you know that u actually can be written as X(x)Y(y)?
 
Dragonfall said:
How do you know that u actually can be written as X(x)Y(y)?

I think that it's more or less an assumption we make when dealing with homogenous PDEs, but I'm probably completely wrong on this.
 

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