2nd order differential equation

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SUMMARY

The discussion focuses on solving the second-order differential equation defined by the expression εy'' - y' = 0 with boundary conditions y(0) = 0 and y(1) = 1. The problem is identified as a perturbation problem, requiring the identification of outer and inner layers. The outer layer is derived by setting ε = 0, leading to the first-order equation y' = 0. The inner layer is approached by substituting x = εnX, resulting in a modified equation involving derivatives with respect to X. The discussion emphasizes the necessity of comparing the outer and inner solutions to obtain a comprehensive understanding of the problem.

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sara_87
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Homework Statement



\epsilony'' - y' = 0
y(0)=0, y(1)= 1


The Attempt at a Solution



this s a perturbation problem, but I'm not sure how to go about doing it
if we let epsilon = 0 we'll go from 2nd order to first order so it's a boundary layer problem... i think
so if that's the case then i have to find the outer and inner layer
to find the outer layer i let epslon =0 and i get y' = 0

then to find the inner layer i let x=\epsilonnX

then after a few steps i got to this:
1/\epsilon d2y/dX2 - 1/\epsilondy/dX

and then solve it normally then find the general solution etc.

and also I'm letting y = y0+ epsilony1 + epsilony2...
and y' = ...
and y''= ...

and subbing them in and solving it too... i can do that, even though there's and epsilon?
and then I'm supposed to compare these together?
 
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i didn't mean for the epsilon to be floating like that
the epsilon is meant to be firmly on the ground... hope this helps
 
Last edited:
You have two sets of solutions, one outer solution and one inner solution.

To find the inner solution, set x=\delta (\varepsilon )X and look for the dominant balance.
 

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