A rocket is launched upward from the top of a 30-foot tall platform. The height of the rocket in feet, $\displaystyle h(t)$, at time $\displaystyle t\geq0$, is given by the equation $\displaystyle h(t)= -16t^2+256t+30$

a) At what time is the rocket at a maximum height?

b) What is the maximum height in feet that the rocket can reach?

Can you show me how to do these?