Fourier Transform: Solving x_3(n) = (n-1)^2x(n)

In summary, the conversation discusses finding the transform of a given discrete function involving a transform pair. The person is initially stumped but then realizes that the function can be rewritten as a simpler form where the transform is already known. This allows them to easily find the transform for the given function.
  • #1
FrogPad
810
0
I am stumped on this...

Given a discrete function, and transform pair: [tex] x(n) \leftrightarrow \hat x (e^{j\omega}) [/tex]

What is the transform of:
[tex] x_3(n) = (n-1)^2 x(n) [/tex]


I really don't know how to do this. I have a table proprety for [itex] nx(n) [/tex], but nothing with [itex] n^2 x(n) [/itex]. The only thing I can think of is expanding it as: [itex] x_3(n) = (n-1)^2x(n) = n^2x(n) - 2nx(n) +x(n) [/itex]... but I'm stuck on the [itex] n^2 [/itex] part. My intuition says that it has something to do with the differentiation property, but I'm really stuck, and can't figure this out. Any help would be awesome. thanks :)
 
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  • #2
Easy. Got it finally.

Just write [tex] x_3(n) = ny(n) [/tex]
where [tex] y(n) = nx(n) [/tex]

and since I have the transform for [itex] nx(n) [/itex], it is cake.
 

FAQ: Fourier Transform: Solving x_3(n) = (n-1)^2x(n)

What is a Fourier Transform?

A Fourier Transform is a mathematical tool that breaks down a signal or function into its individual frequency components. It is commonly used in signal processing and analysis.

What is the purpose of using a Fourier Transform?

The purpose of using a Fourier Transform is to analyze and understand the frequency components of a signal or function. It allows for the identification of dominant frequencies and helps in solving differential equations, such as the given equation x_3(n) = (n-1)^2x(n).

How is the Fourier Transform used in solving x_3(n) = (n-1)^2x(n)?

The Fourier Transform is used to convert the given time domain equation into the frequency domain. This allows for the equation to be solved using algebraic methods, making it easier to find the solution.

What is the relationship between the time domain and frequency domain in Fourier Transform?

The time domain and frequency domain are two different ways of representing the same signal or function. The Fourier Transform allows for the conversion between the two domains, where the time domain represents the signal in terms of time, and the frequency domain represents the signal in terms of frequency.

Are there any limitations to using the Fourier Transform in solving equations?

Yes, there are limitations to using the Fourier Transform. It is most effective for linear and time-invariant systems, and it assumes that the signal is periodic. Additionally, the Fourier Transform cannot always provide an exact solution and may only provide an approximation.

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