The formula h=280t-7t^2 gives the height, h in meters, of a rocket t seconds after take off. The maximum height reached by the rocket is 2800 m. How long will it take the rocket to reach this maximum height?

Answer 1

h = 280t - 7t^2 = 2800.
-7t^2 + 280t - 2800 = 0
Use Quadratic Formula.
t = 20 s.