Hãy xác định H ( Z ) từ hệ thống sau

$\text{H}\left(\text{Z}\right)=1+\beta Z{}^{-1}-\alpha Z{}^{-1}$

$\text{H}\left(\text{Z}\right)=1+\beta Z{}^{-1}+\alpha Z{}^{-1}$

$H\left(Z\right)=1+\beta Z{}^{-1}+\frac{1}{1+\alpha Z{}^{-1}}$

$H\left(Z\right)=\frac{1}{1+\beta Z{}^{-1}}+\alpha Z{}^{-1}$