An explosion causes debris to rise vertically with an initial velocity of 64 feet per second. The polynomial $64 x-16 x^{2}$ describes the height of the debris above the ground, in feet, after $x$ seconds.
a. Find the height of the debris after 3 seconds.
b. Factor the polynomial.
c. Use the factored form of the polynomial in part (b) to find the height of the debris after 3 seconds. Do you get the same answer as you did in part (a)? If so, does this prove that your factorization is correct? Explain.