| Line 91: | Line 91: | ||
<span class="texhtml"> = ''X''(''z'') = (9''z''<sup> + 3</sup> + 4''z''<sup> + 2</sup> + ''z''. The range of the value of z is from negative infinity to positive infinity | <span class="texhtml"> = ''X''(''z'') = (9''z''<sup> + 3</sup> + 4''z''<sup> + 2</sup> + ''z''. The range of the value of z is from negative infinity to positive infinity | ||
| + | |||
| + | === Answer 9 === | ||
| + | |||
| + | <math>X(z) = \sum_{n=-\infinity}^{+\infinity} x[n] z^{-n}</math> | ||
| + | |||
| + | <math>X(z) = \sum_{n=-3}^{+1} x[n] z^{-n}</math> | ||
| + | |||
| + | <span class="texhtml"> = ''X''(''z'') = 9''z''<sup> + 3</sup> + 4''z''<sup> +2</sup> + ''z'' + 1</span> for all z in complex plane | ||
Revision as of 17:13, 12 September 2013
Contents
Practice Problem on Z-transform computation
Compute the compute the z-transform (including the ROC) of the following DT signal:
$ x[n]= n^2 \left( u[n+3]- u[n-1] \right) $
(Write enough intermediate steps to fully justify your answer.)
You will receive feedback from your instructor and TA directly on this page. Other students are welcome to comment/discuss/point out mistakes/ask questions too!
No need to write your name: we can find out who wrote what by checking the history of the page.
Answer 1
x[n] = n2(u[n + 2] − u[n − 1]).
$ X(z) = \sum_{n=-\infty}^{+\infty} x[n] z^{-n} $
$ = \sum_{n=-3}^{0} n^2 z^{-n} $
= 9z3 + 4z2 + z
= z3(9 + 4z − 1 + z − 2)
= X(z) = (9 + 4z − 1 + z − 2) / (z − 3), for all z in complex plane.
Answer 2
Muhammad Syafeeq Safaruddin
x[n] = n2(u[n + 3] − u[n − 1])
x[n] = n2(δ(n + 3) + δ(n + 2) + δ(n + 1) + δ(n))
$ X(z) = \sum_{n=-\infty}^{+\infty} x[n] z^{-n} $
$ X(z) = \sum_{n=-\infty}^{+\infty} n^2(\delta(n+3)+\delta(n+2)+\delta(n+1)+\delta(n)) z^{-n} $
X(z) = 9z3 + 4z2 + z + 1 for all z in complex plane
Answer 3
Write it here.
Answer 4
Write it here.
Answer 5
Tony Mlinarich
$ X(z) = \sum_{n=-\infty}^{+\infty} x[n] z^{-n} $
$ X(z) = n^2(\delta (n+3)+\delta (n+2)+\delta (n+1)+\delta (n)+\delta (n-1)) z^{-n} $
X(z) = 9z3 + 4z2 + z + 1/z<\span>
Back to ECE438 Fall 2013 Prof. Boutin
Answer 7
Yixiang Liu
$ X(z) = \sum_{n=-\infty}^{+\infty} x[n] z^{-n} $
$ X(z) = \sum_{n=-\infty}^{+\infty} n^{2}[{u[n+3]-u[n-1]}]z^{-n} $
This expression equals to zero except n = -3, -2, -1
so $ X(z) = x[-3]z^{3} + x[-2]z^{2} + x[-1]z^{1} $
= 9z^{3} + 4z^{2} + z
Answer 8
Xi Wang
$ X(z) = \sum_{n=-\infty}^{+\infty} x[n] z^{-n} $
= X(z) = (9z + 3 + 4z + 2 + z. The range of the value of z is from negative infinity to positive infinity
Answer 9
$ X(z) = \sum_{n=-\infinity}^{+\infinity} x[n] z^{-n} $
$ X(z) = \sum_{n=-3}^{+1} x[n] z^{-n} $
= X(z) = 9z + 3 + 4z +2 + z + 1 for all z in complex plane
