Answer:
9 seconds
Step-by-step explanation:
You want to find t for h = 0. Using your equation, this is ...
... 0 = -16t² +128t +144
... 0 = t² -8t -9 . . . . divide by -16
... (t +1)(t -9) = 0 . . . factor
... t = -1 or +9 . . . . . . for this problem, the -1 solution is extraneous.
The object will take 9 seconds to hit the ground.
