Are there any values of \$\alpha\$ for which it is possible to find a state-feedback gain for the system by bringing all closed-loop poles to zero? If your answer is affirmative, find a feedback gain yielding the desired closed-loop poles. If you believe there are no such values of α, explain why.Are there values of α for which a state-feedback stabilizing controller can be found?

$$
x(k+1) =\begin{pmatrix}0&1&1\\0&\alpha&0\\1&2&2\end{pmatrix}x(k) + \begin{pmatrix}0\\0\\1\end{pmatrix}u(k)
$$

$$
y(k) = \begin{pmatrix} 0 & 0 & 1 \end{pmatrix} x(k)
$$

From the first part of the question, it is clear that the question wants to know i it possible to design a deadbeat controller, and if I calculate the controllability matrix of A I get 

$$
\begin{pmatrix}0&1&2\\0&0&0\\1&2&5\end{pmatrix}
$$

is this enough to prove that there is no deadbeat controller? If I try and find the feedback vector K = \$\begin{pmatrix} 2 & X & 3\end{pmatrix}\$, were X is a value that can't be extracted from solving the characteristic equation of (**A** - **BK**).Is this further proof of there being no $\alpha$ to enable deadbeat control?


In the second part they are looking for a stabilizing controller (i.e. one that places all closed-loop poles in the open unit circle), How would I find this? I'm not sure what the question wants because from my understanding I though the feedback vector was the one that stabilized the system. Any help appreciated.

Note: Exam revision, Not a homework question.