Suppose that a discrete-time signal x [n] is a sum of complex-exponential signalsx[n] = 3...

Suppose that a discrete-time signal x [n] is a sum of complex-exponential signals

x[n] = 3 + 2ej0.2πn + 2e-πn - 7 jej01πn + 7je-j0.7πn

(a) Make a plot of the DTFT for x [n] using only positive frequencies, i.e., 0 ≤   < 2π.

(b) Suppose that x1[n]= x[n]ej0.4πn. Make a plot of the DTFT for x1[n] using only positive frequencies.

(c) Suppose that x2[n] = (-l)n x[n]. Make a plot of the DTFT for x2[n] using only positive frequencies.