Inverse Laplace Transform of s2-5/s3+4s2+3s

In summary, the conversation is about finding the inverse Laplace transform of the expression s2-5 / s3+4s2+3s and using partial fractions to split it up into A/(s+1) + B/(s+1)2 + C/(s+1)3 + D/(s+1)4 to solve for the coefficients A, B, C, and D. It is suggested to use either distinct first order factors or put in multiple values for s to simplify the equations.
  • #1
drsmoothe2004
7
0

Homework Statement



s2-5 / s3+4s2+3s


Homework Equations



find the inverse laplace transform


The Attempt at a Solution


for the denominator, it can be factored out to s(s+3)(s+1) or one could complete the square and thus the denominator would be s(s+2)2-1. neither of this help in finding the laplace transform
 
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  • #2
Factor it into s(s+3)(s+1), then split into partial fractions.
 
  • #3
haha, thanks. just as i received your post, i actually figured it out. but thank you for taking the time to look at my problem
 
  • #4
another problem

1. Homework Statement
3s / (s+1)4


2. Homework Equations
find the inverse laplace


3. The Attempt at a Solution
i used partial fractions to split it up into A/(s+1) + B/(s+1)2 +c/(s+1)3 +D/(s+1)4

which in turn gives me A(s+1)3 + B(s+1)2 + C(s+1) + D = 3s
i plugged in s=-1 to get D=-3, i don't know how to find A, B or C (sad i know) maybe its just a late night and my brain isn't working well because i can't seem to figure it out
 
  • #5
drsmoothe2004 said:
another problem

1. Homework Statement
3s / (s+1)4


2. Homework Equations
find the inverse laplace


3. The Attempt at a Solution
i used partial fractions to split it up into A/(s+1) + B/(s+1)2 +c/(s+1)3 +D/(s+1)4

which in turn gives me A(s+1)3 + B(s+1)2 + C(s+1) + D = 3s
i plugged in s=-1 to get D=-3, i don't know how to find A, B or C (sad i know) maybe its just a late night and my brain isn't working well because i can't seem to figure it out

As long as you have distinct first order factors, you can put in a single value for x and immediately reduce to one coefficient. With powers or irreducible quadratics, its not so trival but still not hard.

Probably easiest: put in 3 more values for s, say s= 0, s= 1, and s= 2, to get 3 linear equations in A, B, C. They won't reduce to three separated equations but still you can solve them.

Harder: go ahead and multiply everything out: [itex]A(s^3+ 3s^2+ 3s+ 1)+ B(s^2+ 2s+ 1)+ C(s+ 1)- 3[/itex][itex]= As^3+ 3As^2+ 3As+ A+ Bs^2+ 2Bs+ B+ Cs+ C- 3= 3s[/itex].

Now combine "like terms" to get 3 equations for A, B, and C.
 
  • #6
3s = 3(s+1) - 3
 
  • #7
Count Iblis said:
3s = 3(s+1) - 3

Yes, it looks like a shifting property would be the best to tackle this problem.
 

FAQ: Inverse Laplace Transform of s2-5/s3+4s2+3s

What is the Inverse Laplace Transform of s2-5/s3+4s2+3s?

The Inverse Laplace Transform of s2-5/s3+4s2+3s is a mathematical operation that converts the expression back to its original form in the time domain. In other words, it finds the function in the time domain that would result in the given expression when transformed to the Laplace domain.

What is the process for finding the Inverse Laplace Transform of s2-5/s3+4s2+3s?

The process for finding the Inverse Laplace Transform involves using a table of Laplace transforms to identify the inverse transform of each term in the expression. The inverse transform is then combined using specific rules and properties to obtain the final answer in the time domain.

What are the common properties used in finding the Inverse Laplace Transform?

The common properties used in finding the Inverse Laplace Transform include linearity, time shifting, frequency shifting, and differentiation. These properties allow us to manipulate the expression and simplify it to find the inverse transform.

What are the challenges in finding the Inverse Laplace Transform of s2-5/s3+4s2+3s?

One of the main challenges in finding the Inverse Laplace Transform of s2-5/s3+4s2+3s is identifying the correct inverse transforms of each term in the expression. This requires a good understanding of the table of Laplace transforms and the properties involved.

How is the Inverse Laplace Transform of s2-5/s3+4s2+3s used in science?

The Inverse Laplace Transform of s2-5/s3+4s2+3s is used in various scientific fields, including engineering, physics, and mathematics. It is used to solve differential equations and model real-world systems, such as electrical circuits and mechanical systems.

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