1. The problem statement, all variables and given/known data Is the system y[n] = x[n] - x[n-1] time invariant? 2. Relevant equations 3. The attempt at a solution I say no, but there's one thing I don't understand. I think if you shifted the input, and then ran those samples through the system, you'd get x[n-n0] - x[n-1]. If you ran the signal through the system first, then shifted the output, you'd get x[n-n0] - x[n-n0-1]. This is my thinking, is it incorrect?