Choose the equation that is based on the description “nine more than twelve times a number equals one.” 9x + 12 = 1 9x + 1 = 12 12x + 1 = 9 12x + 9 = 1

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).