Given the expression 5a2b2 − 13ab + 7a3 − 4b, do the following as instructed below: A: Write the polynomial in descending order.
B: Classify the polynomial by the number of terms.
C: State the degree of the polynomial.

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).