How do I approach this?

Q\" , For LTI systems, Show that (A, C) is observable if and only if (A, C) is observable. 0 0 This is no longer true for LTV system. Consider the LTV system with A = ( 0 _1 )andC= ( 1 e15 ) as a counterexample. a) Show that 11\") = 1 e2t 331(0) 2 00:) $1(U) 1W) 0 2_2t 932(0) $23)) b) Show that 0(t) is invertible for every t and then conclude that we can recover the initial condition from the output. c) Obtain the solution for y(t) with (A,C) and conclude that initial condition can no longer be uniquely determined