Given x[n] = {..., 12, 9, 6, 3, 6, 9, 12, 9, 6, 3, 6, 9, 12,...},

a. Compute its DTFS expansion. Hint: [n] has period = 6, is real, and is an even

function.

b. Compute its average power in the time domain.

c. Compute its average power in the frequency domain. By Parseval's theorem, both

should match.

Note: fft in Matlab can be used to check the results, but all work needs to be shown for full credit.