The region of convergence (ROC) of the Z-transform of the signal x[n]=0.5nu[n]−0.75nu[−n−1]{\displaystyle x[n]=0.5^{n}u[n]-0.75^{n}u[-n-1]} is 0.5&lt;|z|&lt;0.75{\displaystyle 0.5&lt;\left|z\right|&lt;0.75} and is shown in blue.
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