Is my unit step function correct for solving this differential equation?

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SUMMARY

The discussion centers on solving the differential equation y'' - 4y' - 32y = {1 when 0 <= t < 1 and 0 when t >= 1} with initial conditions y(0) = y'(0) = 0. The user is attempting to apply the Laplace transform but is uncertain about the correct formulation of the unit step function. The correct representation for the right-hand side should be u(t) - u(t-1), which accurately captures the piecewise nature of the function. The user's initial approach using u1(t) was incorrect, leading to confusion in the solution process.

PREREQUISITES
  • Understanding of differential equations and initial value problems
  • Familiarity with Laplace transforms and their properties
  • Knowledge of the unit step function and its applications
  • Basic skills in solving piecewise functions
NEXT STEPS
  • Study the properties of the unit step function, specifically u(t) and u(t-a)
  • Learn how to apply the Laplace transform to piecewise functions
  • Review solving differential equations using Laplace transforms
  • Practice problems involving initial value problems with piecewise continuous functions
USEFUL FOR

Students studying differential equations, particularly those learning about Laplace transforms and piecewise functions. This discussion is beneficial for anyone seeking to clarify the use of the unit step function in solving differential equations.

gbuitkus
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Homework Statement


y''-4y'-32y={1 when 0<=t<1 and 0 when 1<=t
y(0)=y'(0)=0


Homework Equations





The Attempt at a Solution


s2L(y) -4sL(y)-32 L(y)=u1(t)

I am just struggling to figure out if my unit step function is correct.

Solving for L(y) I get:
(e-s) / (s(s2 -4s-32))
but it says I am wrong so I am pretty sure I am doing something wrong with the unit step function
 
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gbuitkus said:

Homework Statement


y''-4y'-32y={1 when 0<=t<1 and 0 when 1<=t
y(0)=y'(0)=0

Homework Equations


The Attempt at a Solution


s2L(y) -4sL(y)-32 L(y)=u1(t)

I am just struggling to figure out if my unit step function is correct.

Solving for L(y) I get:
(e-s) / (s(s2 -4s-32))
but it says I am wrong so I am pretty sure I am doing something wrong with the unit step function

You didn't explain what your notation ##u_1(t)## means. Is it ##u(t-1)##? What you want on the right side is ##u(t)-u(t-1)##.
 

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