Answer:
A) 0.72
Step-by-step explanation:
You want to find t when h = 0, so you're solving ...
0 = -16t^2 +6t +4
The quadratic formula tells you the solution is ...
t = (-b +√(b² -4ac))/(2a) . . . . . . where you have a=-16, b=6, c=4
t = (-6 -√(36 -4·(-16)·4))/(2(-16)) = (-6 -√292)/-32
t ≈ 0.7215 ≈ 0.72 . . . . seconds
_____
Comment on the problem statement
It appears the velocity number of 36 ft/s is irrelevant, as the equation tells you the initial upward speed of the ball is 6 ft/s.
