An LTI system is described by the difference equation y[n] = 2x[n] - 2x [n 1] + 2x[n 2] a. Determine an equation for the frequency response Hew) and express it in the form where Re H(e) = R(e) is a real function and no is an integer. e-Jung e b. H (ew) is a periodic function of ; determine the period. c. Plot the magnitude of H (ew) as a function of @ for - < < 37. Do this by hand, and then check with the MATLAB function freqz. d. Find all frequencies in the interval -