Xác định x ( n ) . Biết X ( Z ) = 1 1 − a Z − 1 + b Z − 3 voi a < | Z | < 3

$x\left(n\right)=b\cdot 3{}^n\cdot u\left(-n-1\right)-a{}^n\cdot u\left(n\right)$

$\text{x}\left(\text{n}\right)=\text{a}{}^{\text{n}}\cdot \text{u}\left(\text{n}\right)-\text{b}\cdot 3{}^{\text{n}}\cdot \text{u}\left(-\text{n}-1\right)$

$x\left(n\right)=a{}^n\cdot u\left(n\right)+b\cdot 3{}^n\cdot u\left(-n-1\right)$

$\text{x}\left(\text{n}\right)=\text{b}\cdot 3{}^{\text{n}}\cdot \text{u}\left(\text{n}\right)+\text{a}{}^{\text{n}}\cdot \text{u}\left(\text{n}\right)$