Need help with math homework guys please help

Question

A person standing close to the edge on top of a 108-foot building throws a ball vertically upward. The quadratic function  models the ball's height about the ground, , in feet,  seconds after it was thrown.

a) What is the maximum height of the ball?

b) How many seconds does it take until the ball hits the ground?

Answer 1

 h(t)=−16t2+132t+108

a.) The velocity, h'(t) is 0 at the maximum height of the ball,

h'(t) = -32t +132 = 0

t = 4.125 seconds

b) h(t) = 0 when the ball hits the ground,

then t = 9 seconds