A fireworks rocket is launched into the air.[br][br]Its height above the ground, in meters, after x seconds is modeled by the function [math]f\left(x\right)=-x^2+8x[/math].[br]Represent graphically the function f in the Cartesian coordinate system xOy.[br]
What is the height of the rocket after 1 second?[br]
What is the height of the rocket after 3 second?[br]
At what time does the rocket reach its maximum height?
What is the maximum height reached by the rocket?
After how many seconds does the rocket return to the ground?