Question:

If the input is \[ x[n]=-u[n]+2u[n-3]-u[n-6] \] and impulse response is \[ h[n]=u[n+1]-u[n-10] \] of an LTI system, then the output \(y[n]\) in the interval \(5\le n\le9\) is

Show Hint

When one sequence is rectangular, convolution can often be interpreted as a moving summation window.
Updated On: Jun 25, 2026
  • \(y[n]=0\)
  • \(y[n]=-(n+2)\)
  • \(y[n]=n-4\)
  • \(y[n]=n-9\)
Show Solution
collegedunia
Verified By Collegedunia

The Correct Option is D

Solution and Explanation

Concept: The output of an LTI system is obtained using convolution: \[ y[n]=x[n]*h[n]. \] First simplify the input sequence.

Step 1:
Determine the values of \(x[n]\).
\[ x[n]=-u[n]+2u[n-3]-u[n-6]. \] Hence, \[ x[n]= \begin{cases} 0,& n \\ -1,& 0\le n \\ 1,& 3\le n \\ 0,& n\ge6 \end{cases} \]

Step 2:
Determine the values of \(h[n]\).
\[ h[n]=u[n+1]-u[n-10]. \] Thus \[ h[n]=1,\qquad -1\le n\le 9. \]

Step 3:
Evaluate convolution in the interval \(5\le n\le9\).
Since \(h[n]\) is a rectangular sequence, convolution reduces to summing the values of \(x[k]\) lying in the window. For \(5\le n\le9\), \[ y[n] = -(3)+(6-n) \] which simplifies to \[ y[n] = n-9. \]

Step 4:
Write the final answer.
\[ \boxed{y[n]=n-9} \]
Was this answer helpful?
0
0