A First, solve the equation
[tex]{ - 16t}^{2} + 96t = 80[/tex]
Solving will give:
5 and 1, the largest number is 5, so after 5 seconds it reaches 80 feet for the second time.
B Solve the equation
[tex]{ - 16t}^{2} + 96t = 0[/tex]
Solving gives:
t = 0 and t = 6, since it cannot hit the ground within 0 seconds, your awnser is: after 6 seconds it will hit the ground.
C Find the maximum.
Use [tex]\frac{-b}{2a}[/tex] to find the time in seconds.
This gives: t = 3
Filling in t = 3 gives: 144 feet.
The max. height is 144 ft.
