7.24. Let yu (t) represent the response of a CTLTI system to a unit-step input signal e (t) = u (t). Determine the system function for each system the unit-step response of which is given below. Afterwards find a differential equation for each system. a. yu (t) = etu(t) yu (t) = (1 - e ) u (t) C. yu (t) = (et - e-2t) 1 (1) P yu (t) = (1 -et+ 2e-2) u(t) e. yu (t) = [1 -0.3e t cos (2t)] u (t)