Cho x ( n ) có Z T [ x ( n ) ] = X ( Z ) thì:

$ZT\left[nx\left(n\right)\right]=-Z\frac{dX\left(Z\right)}{dZ}$

$ZT\left[nx\left(n\right)\right]=Z\frac{dX\left(Z\right)}{dZ}$

$ZT\left[nx\left(n\right)\right]=-Z\frac{dX\left(-z\right)}{dZ}$

$ZT\left[nx\left(n\right)\right]=Z\frac{dX\left(-z\right)}{dZ}$