6. a)
Can this system be time-invariant? Explain.
Answer)System is not Time Invariant. Because by time shifting the inputs and outputs. First delay the input by delta(d), then delay separately the output, the two cases outputs are not the same.
b)
Assuming that this system is linear, what input X[n] would yield the output Y[n]=u[n-1]?
Answer) X[n] = u[n]
