Hz=tf([0.74 -2.54 2.5216],[1 0 0.64],0.1)
subplot(2,1,1);
pzmap(Hz);
hold on;
subplot(2,1,2);
impz([0.74 -2.54 2.5216],[1 0 0.64]);
hold on;
n=0:1:49;
Xn=(-2*(0.3).^n)+2*(0.8).^n;
y=filter([0.74 -2.54 2.5216],[1 0 0.64],Xn);
plot(y);