The formula h=300t- 5t^2 gives the height, h in meters, of a rocket the seconds after take off. The maximum height reached by the rocket is 4500m. How long will it take the rocket to reach this maximum height?

Answer 1

H=300t-5t^2=4500
60t-t^2-900=0
-t^2+60t-900=0
multiply by negative sign
t^2-60t+900=0
(t^2-30t)-(30t+900)=0
t(t-30)-30(t-30)=0
(t-30)^2=0
divide tru by (t-30)
you get t=30