a)
Yk[n]=(k+1)^2 d[n-(k+1)]
Yes, the system is time invariant because the system does not have a scaling affect on the time part of the function. For example, if the system were written as such:
Yk[n]=(k+1)^2 d[2n-(k+1)]
Then it would not be time invariant because (k+1) would be scaled or un-scaled depending on the order of operation.
b) k would have to be 0 because only then is d[2n-(k+1)] not affected.
