Question 4 Consider the system below: $$ \begin{array}{1} \dot{x}_{1}=3 x_{1}-7 x_{2} \ \dot{x}_{2}=\alpha x_{1}+4 x_{2} \end{array} $$ with output $$ y=\alpha x_{1}+3 x_{2} $$ where $\alpha$ is a costant. Find the values of $\alpha$ for which the system is completely observable. CS.JG. 121