$[40$ pts$]$ Given the open$-$loop transfer function

$G(s)=\frac{1}{s^2-4s-4}$

a$)$ Assuming zero initial conditions, find a state$-$space realization in the controllable canonical form.

b$)$ Design a full state feedback controller $u=-Kx$ that places the poles of the closed$-$loop system to $s_{1,2}=-2.$