Question

The system $G\left(s\right)=\frac{0.8}{s^2+s-2}$ is subjected to step input. The system output y(t) at $t\to \infty$, is

• A. 0.8
• B. 0.4
• C. -0.4
• D. unbounded

Answer 1

The correct option is D unbounded

For the final value to exist, all the poles should lie on the L.H.S. Thus the system should be stable. But here,

$G\left(s\right)=\frac{0.8}{s^2+s-2}=\frac{0.8}{(s+2)(s-1)}$

one pole S =1 , lie on R.H.S, thus the system is unstable.

$\therefore$ The final value is unbounded.