Which of the following systems is time invariant?
A. y(t) = x(2t) + x(t)
B. y(t) = x(t) + x(1-t)
C. y(t) = -x(t) + x(1-t)
D. y(t) = x(t) + x(t-1)
Answer:A
Which of the following systems is time invariant?
A. y(t) = x(2t) + x(t) B. y(t) = x(t) + x(1-t) C. y(t) = -x(t) + x(1-t) D. y(t) = x(t) + x(t-1)
Explanation: In each of a, b and c there is a negative sign of t involved, which means a backward shift of t-0 in time, would mean a forward shift in each of them. However, only in d, the backward shift will remain as backward, and undiminished.