Determine the equations of motion if the following is true. (a) the mass is initially released from rest from a point 1 meter below the equilibrium position x(t)=− 2 1 ​ e −9t + 2 3 ​ e −3t m (b) the mass is initially released from a point 1 meter below the equilibrium position with an upward velocity of 12 m/s x(t)= 2 5e −3t ​ − 2 9e −9t ​ x ​ m