A ball is thrown straight up from the top of a building 128 ft tall with an initial velocity of 80 ft per second. The height

s(t) (in feet)
of the ball from the ground, at time t (in seconds), is given by
s(t) = 128 + 80t − 16t^2.
Find the maximum height attained by the ball

1 answer

max height is on the axis of symmetry of the parabola ... x = -b / (2a)

tmax = -80 / (2 * -16) = 2.5 s

plug the time into the height equation to find max height