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A linear discrete-time system has the characteristic equation, z3 – 0.81z = 0
The system—
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- is stable
- is marginally stable
- is unstable
- stability cannot be assessed from the given information.
- is stable
Correct Option: A
Given equation z3 – 0·81z = 0
z(z – 0·81) = 0
z(z – ·9) (z + ·9) = 0
z = 0, 0·9, – 0·9
since all the roots lies inside the unit circle.
Hence the given system is stable.
