5) find the missing value.
a) 4x (5 + 3) = (4 * 5) + (*)
b) 3 < (3 + 2) = ( ) + (3 x 2)
c) 4x (4 + 3) = () + (4 * 3)
d) 6x (5 + 3) = (6 * 5) + (o)
e) 6+ (1) = (6 * 5) + (6 * 3)
f) 5( ) = (5 6) + (5 x 3)

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).