First order linear non-homogeneous PDE

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SUMMARY

The discussion focuses on solving the first order linear non-homogeneous partial differential equation (PDE) given by y²(ux) + x²(uy) = 2y², with the initial condition u(x, y) = -2y on y³ = x³ - 2. The general solution consists of a particular solution and the general solution to the associated homogeneous PDE, which is y²(ux) + x²(uy) = 0. The characteristic equation dy/dx = x²/y² leads to the general solution u = f(y³ - x³). A suggested particular solution is u = 2x, although the discussion seeks a more systematic approach for finding particular solutions to similar PDEs.

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kingwinner
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Homework Statement


Find the general solution to the PDE and solve the initial value problem:
y2 (ux) + x2 (uy) = 2 y2, initial condition u(x, y) = -2y on y3 = x3 - 2


2. Homework Equations /concepts
First order linear non-homogeneous PDEs


The Attempt at a Solution


I know that the general solution to the non-homogeneous PDE = a particular soltuion to it + the general solution to the assoicated homogenous PDE, so I first consider to assocatied homogeneous equation:
y2 (ux) + x2 (uy) = 0

The characteristic equation is dy/dx = x2/y2
And the solution to this ODE is y3 - x3 = C where C is an arbitrary constant.
So the general solution to the homogeneous equation is u = f(y3 - x3) where f is arbitrary differentiable function of one variable.
But then I am stuck. How can I find a particular solution to the original non-homogeneous PDE? Is there a systematic way to find one such solution?

Any help is appreciated! :)
 
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Can someone please help? I am still stuck on this problem... :(
 
kingwinner said:
Find the general solution to the PDE...
y2 (ux) + x2 (uy) = 2 y2
...

How can I find a particular solution to the original non-homogeneous PDE? Is there a systematic way to find one such solution?

Any help is appreciated! :)

I don't know about any systematic ways, but just looking at it, if you could find a u such that ux = 2 and uy = 0 that would do it. And that's easy.
 
LCKurtz said:
I don't know about any systematic ways, but just looking at it, if you could find a u such that ux = 2 and uy = 0 that would do it. And that's easy.
Then, I think u=2x will work as a particular solution.

But really, can anyone suggest a more general/systematic way to solve it that would work also for more complicated first order linear PDEs?

Thanks!
 

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