Correct Answer : Option (A) : y(n) = 3x(n) – 2x(n-1)
Explanation : We know that, for a causal system, output must depend on present and past but not on future.
For y (n) = 3x (n) + 2x (n+1), we can observe that output depends on future because of the term x (n+1). Hence, not a causal system.
For y (n) = 3x (n+1) + 2x (n-1), we can observe that output depends on future because of the term x (n+1). Hence not a causal system.
For y (n) = 3x (n+1) + 2x (n-1) + x (n), we can observe that output depends on future because of the term x (n+1). Hence not a causal system.
For y (n) = 3x (n) – 2x (n-1), we can observe that output depends on present and past but not on the future. Hence, it is a causal system.
