Find the inverse Laplace transform?

In summary, we need to find the inverse Laplace transform of F(s)=(8s^2-4s+12)/(s(s^2+4)), which can be solved by using the equation A/s+(Bs+C)/(s^2+4). After plugging in specific values for A, B, and C, the inverse Laplace transform is found to be f(t)=3-2 sin 2t+5 cos 2t.
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Homework Statement


Find the inverse Laplace transform of F(s)=(8s^2-4s+12)/(s(s^2+4)).


Homework Equations


A/s+(Bs+C)/(s^2+4)
8s^2-4s+12=A(s^2+4)+(Bs+C)(s)=As^2+4A+Bs^2+Cs=s^2(A+B)+Cs+4A
8=A+B
C=-4
A=3
B=5
L^-1 (3/s)+L^-1 ((5s-4)/(s^2+4))
=3+ (Now I'm stucked.)



The Attempt at a Solution


The answer is f(t)=3-2 sin 2t+5 cos 2t.
 
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  • #2
[tex]
\frac{5s - 4}{s^2 + 4} = 5\frac{s}{s^2 + 4} - 2\frac{2}{s^2 + 4}
[/tex]

Hopefully you should recognise the two terms on the right hand side as being Laplace transforms.
 
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  • #3
Yes, I did. Thank you.
 

FAQ: Find the inverse Laplace transform?

1. What is an inverse Laplace transform?

An inverse Laplace transform is a mathematical operation that takes a function in the complex frequency domain and transforms it back into the time domain. It is the inverse operation of the Laplace transform and is used to solve differential equations and analyze dynamic systems.

2. How do you find the inverse Laplace transform?

The inverse Laplace transform can be found using various techniques, including partial fraction decomposition, convolution, and the residue theorem. The specific method used depends on the form of the function in the complex frequency domain.

3. What is the Laplace transform table and how is it used to find the inverse Laplace transform?

The Laplace transform table is a list of common functions and their corresponding transforms. It can be used to simplify the process of finding the inverse Laplace transform by matching the function in the table with its transform and using the properties of the Laplace transform to manipulate the equation.

4. How is the inverse Laplace transform useful in scientific research?

The inverse Laplace transform is a powerful tool in scientific research as it allows for the analysis and modeling of dynamic systems. It is commonly used in fields such as engineering, physics, and mathematics to solve differential equations and analyze the behavior of systems over time.

5. Are there any limitations to using the inverse Laplace transform?

Yes, there are some limitations to using the inverse Laplace transform. One limitation is that it is only applicable to functions that have a Laplace transform. Additionally, for some functions, it may be difficult or impossible to find the inverse Laplace transform using traditional methods, and numerical techniques may be needed instead.

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