the answer to question (a)(?)

4. The discrete-time state-space representation obtained by sampling a continuous-time system with a zero-order hold at a sampling period 7= 0.1 second is given by x , ( k + 1 ) X , ( k ) = A LX, (k + 1) + Bu(k) X 2 ( k ) y(k) = C x, ( k ) 7 * 2 ( k ) 4 where A = ,B= ,C=[2 2], a is a real number and X, (k) 7 , u(k) and * 2 (k ) y(k) are the states, input and output variables, respectively. (a) (i) Determine the condition on a for the system to be controllable