a toy rocket is fired upwards and its height h after t seconds is given by the formula h(t)= -4t^2+120t

Question

Find the following

a. what is the height 3 seconds after the launch?

b. what is the maximum height attained by the firecracker?

c. when does the firecracker hit the ground? what is the implied domain of this function?

Answer 1

max height is when t = 120/8 = 15 seconds

it hits the ground in twice that = 30 seconds

max h = -4(15)^2 + 120(15) = -900 + 1800 = 900 feet high implied domain is 0<t<30

in 3 seconds it's 360-36 = 224 feet high