Add. Your answer should be an expanded polynomial in standard form. (- 4b ^ 2 + 8b) + (- 4b ^ 3 + 5b ^ 2 - 8b) =

Amass weighing 16 pounds stretches a spring 8/3 feet. the mass is initially released from rest from a point 2 feet below the equilibrium position, and the subsequent motion takes place in a medium that offers a damping force that is numerically equal to 1/2 the instantaneous velocity. find the equation of motion if the mass is driven by an external force equal to f(t)=cos(2t).