how long will it take a rocket to reach its maximum height

Question

during an independance day fireworks show, the height h in meters of a specific rocket after t seconds can be modeled by h=-4.9(t-4)squared +80

Answer 1

The first term ( -4.9(t-4)^2 ) can never be positive, so the maximum height of 80 meters is achieved when t = 4.  

 

So the rocket will reach its maximum height after 4 seconds.