Applying Partial Fractions to Solve Laplace Step Function Problems

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SUMMARY

The discussion focuses on applying partial fractions to solve Laplace transform problems involving step functions. The specific problem presented is y'' + y = f(t), where f(t) is defined piecewise as 1 for t < π/2 and 0 for t ≥ π/2. The solution involves finding the Laplace transform L{y} = (1 - e^(-(π/2)s) + s) / (s(s² + 1)) and separating it into partial fractions. Participants emphasize the importance of determining constants A, B, and C in the expression 1 / (s(s² + 1)) to complete the solution.

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  • Understanding of Laplace transforms and their properties
  • Knowledge of partial fraction decomposition techniques
  • Familiarity with solving second-order differential equations
  • Basic trigonometric functions and their relationships
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  • Learn how to perform Laplace transforms on piecewise functions
  • Study the method of partial fractions in detail
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Students and professionals in mathematics, engineering, and physics who are working with differential equations and Laplace transforms, particularly those focusing on step functions and their applications.

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step function - laplace...

Homework Statement


y"+y = f(t)

f(t) = 1, t<pi/2
0, pi/2<=t<infinity

The Attempt at a Solution



i now have L{y} = \frac{1-e^(-(pi/2)s)+s}{s(s^2+1)}

but how do i separate them and finish the problem?

thanks
 
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Use partial fractions like always.
\frac{1}{s(s^2+ 1)}= \frac{A}{s}+ \frac{Bs+ C}{s^2+ 1}

Find A, B, and C.
 


HallsofIvy said:
Use partial fractions like always.
\frac{1}{s(s^2+ 1)}= \frac{A}{s}+ \frac{Bs+ C}{s^2+ 1}

Find A, B, and C.

so no i have f(t) = 1-cos(t)+sin(t) - L{\frac{e^(pi*t/2)}{s(s^2+1)}}

how do i get the last laplace?
 
Last edited:

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