Ler x[n] be a real-valued, causal, finite-length sequence with length N = 3. Find two choices for

Question:

Ler x[n] be a real-valued, causal, finite-length sequence with length N = 3. Find two choices for x[n] such that the real part of the discrete Fourier transform X_R[k] matches that shown in Figure. Note that only one of your sequences is ?periodically causal? according to the definition in Section 11.2, where x[n] = 0 for N/2