(New page: Problem 1 is the problem I received the least amount of points on, therefore I will solve it. Is the signal <math>x(t) = \sum^{- \infty}_{\infty} \frac{1}{(t+2k)^2 + 1)}</math> periodic...)
 
 
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Is the signal
 
Is the signal
  
<math>x(t) = \sum^{- \infty}_{\infty} \frac{1}{(t+2k)^2 + 1)}</math>
+
<math>x(t) = \sum^{\infty}_{k = - \infty} \frac{1}{(t+2k)^2 + 1)}</math>
  
 
periodic? Answer yes/no and justify your answer mathematically.
 
periodic? Answer yes/no and justify your answer mathematically.
Line 9: Line 9:
 
Yes, because:
 
Yes, because:
  
<math>x(t+2) = \sum^{- \infty}_{\infty} \frac{1}{(t+2+2k)^2 + 1}</math>
+
<math>x(t+2) = \sum^{\infty}_{k = - \infty} \frac{1}{(t+2+2k)^2 + 1}</math>
  
<math>= \sum^{- \infty}_{\infty} \frac{1}{(t+2(k+1))^2 + 1}</math>  
+
<math>= \sum^{\infty}_{k = - \infty} \frac{1}{(t+2(k+1))^2 + 1}</math>  
  
 
let r = k + 1
 
let r = k + 1
  
<math>= \sum^{- \infty}_{\infty} \frac{1}{(t+2r)^2 + 1} = x(t)</math>
+
<math>= \sum^{\infty}_{r = - \infty} \frac{1}{(t+2r)^2 + 1} = x(t)</math>

Latest revision as of 14:19, 15 October 2008

Problem 1 is the problem I received the least amount of points on, therefore I will solve it.

Is the signal

$ x(t) = \sum^{\infty}_{k = - \infty} \frac{1}{(t+2k)^2 + 1)} $

periodic? Answer yes/no and justify your answer mathematically.

Yes, because:

$ x(t+2) = \sum^{\infty}_{k = - \infty} \frac{1}{(t+2+2k)^2 + 1} $

$ = \sum^{\infty}_{k = - \infty} \frac{1}{(t+2(k+1))^2 + 1} $

let r = k + 1

$ = \sum^{\infty}_{r = - \infty} \frac{1}{(t+2r)^2 + 1} = x(t) $

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