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

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SUMMARY

The discussion focuses on finding the Fourier Transform of the discrete function x_3(n) = (n-1)^2 x(n). The user initially struggles with the transformation but realizes that by rewriting x_3(n) as x_3(n) = n y(n), where y(n) = n x(n), they can leverage the known transform for n x(n). This approach simplifies the problem, allowing for an easier calculation of the Fourier Transform.

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  • Understanding of Fourier Transform properties for discrete functions
  • Familiarity with the differentiation property of Fourier Transforms
  • Knowledge of discrete-time signals and systems
  • Experience with manipulating mathematical expressions involving sequences
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  • Learn about the Fourier Transform of n x(n) and its implications
  • Explore additional properties of Fourier Transforms for polynomial sequences
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Students and professionals in signal processing, electrical engineering, and applied mathematics who are working with Fourier Transforms and discrete-time signals.

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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 :)[/itex]
 
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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.
 

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