Figure 1 shows a mass m in equilibrium between two stretched helical springs on a smooth horizontal surface. k_1 and k_2 are the force constants of the springs and e_1 , e_2 are their respective equilibrium extensions. The mass m is displaced X to one side ( X is smaller than e_1 and e_2 ), and then released. how you show that the acceleration (a) of the mass when its displacement from the equilibrium position is x obey the following equation : a = - [ (k_1) + (k_2) ]*x / m Please show me step by step !! thanks you.