When a 7 kg mass is attached to a spring whose constant is 112 N/m, it comes to rest in the equilibrium position. Starting at t = 0, a force equal to f(t) = 42e 3t cos 6t is applied to the system. In the absence of damping. (a) find the position of the mass when t = 7. (b) what is the amplitude of vibrations after a very long time? Problem #7(a): Round your answer to 4 decimals. Problem #7(b): Round your answer to 4 decimals.