Laplace Transforms with IVP and linear first ODE

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SUMMARY

The discussion focuses on solving the linear first-order ordinary differential equation (ODE) derived from the second-order equation y'' + ty' - y = 0 using Laplace transforms. The initial conditions provided are y(0) = 0 and y'(0) = 3. The transformation leads to the equation -sY'(s) + (s^2-2)Y(s) = 3, where the integrating factor P(s) is defined as (s^2-2)/-s. Participants emphasize the need to correctly integrate P(s) to find the solution, addressing common errors in the approach.

PREREQUISITES
  • Understanding of Laplace transforms and their application in solving differential equations.
  • Familiarity with first-order linear ordinary differential equations (ODEs).
  • Knowledge of integrating factors and their role in solving ODEs.
  • Basic calculus skills, particularly integration techniques.
NEXT STEPS
  • Study the process of finding integrating factors for first-order linear ODEs.
  • Learn about the application of Laplace transforms in solving initial value problems (IVPs).
  • Explore advanced integration techniques to handle complex functions.
  • Review common mistakes in applying Laplace transforms to differential equations.
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Students studying differential equations, mathematicians, and educators looking to deepen their understanding of Laplace transforms and their applications in solving initial value problems.

Lee49645
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Homework Statement


y'' + ty' - y = 0

plugging in the known Laplace formuals i get this...
[s^2Y(s) - sy(0) - y'(0)] + [-sY'(s) - Y(s)] - Y(s) = 0


Homework Equations



y(0) = 0
y'(0) = 3

The Attempt at a Solution


simplying to a linear first order DE
-sY'(s) + (s^2-2)Y(s) = 3

Y'(s) + [(s^2-2)/-s]Y(s) = 3

now, according to my textbook "P(x)" = [(s^2-2)/-s], and i need to find the integrating factor by integrating P(x)

use e^(p(x)) then etc.

the problem I am having is how to approach integrating p(x). i tried dividing each term by s and integrating them separately but plugging them into e causes hectic problems.

is there a different way to approach this?
 
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Lee49645 said:

Homework Statement


y'' + ty' - y = 0

plugging in the known Laplace formuals i get this...
[s^2Y(s) - sy(0) - y'(0)] + [-sY'(s) - Y(s)] - Y(s) = 0

I think you have an extra [itex]-Y(s)[/itex] in here.


now, according to my textbook "P(x)" = [(s^2-2)/-s], and i need to find the integrating factor by integrating P(x)

Ermm...you mean [itex]P(s)[/itex] right?:wink:


i tried dividing each term by s and integrating them separately but plugging them into e causes hectic problems.

That's the correct approach...what do you get when you do this (after correcting your 1st error)?
 

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