part a
This system can not be time invariant.
Pf:
Delay then system yields the constant $ (K+1+n_o)^2 $, but the system then delay yields a constant $ (K+1)^2 $
part b
Since $ X[n]=\delta[n] $ yields $ Y[n]=\delta[n-1] $, we can replace the unit impulses with unit steps because the system is linear,
so $ X_[n]=u[n] $ yields $ X[n]=u[n-1] $
