12. (20 pts) Find the transfer function X(s)/X(s) of the mechanical system shown in Figure 8-24. Obtain the displacement x,(t) when the input .x(t) is a step displacement of magnitude X, occurring at = 0. Assume that x,(0) = 0. The displacement .x,(t) is measured from the equilibrium position before the input .x,(/) is given. k₁ b₁ k₂ www www x Figure 8-24 Mechanical system.