5.6. Consider a random process whose autocorrelation sequence is defined by,

r (k) (k) (0.9) cos( k / 4) k x =δ + π . The first six autocorrelation values are, rx [ ]
T = 2.0 0.6364 0 −0.5155 −0.6561 −0.4175 .
Solve the equations for a first-order three step linear predictor and compute the mean square error.