Answer:
9 seconds
Step-by-step explanation:
When the object is on the ground it's height = 0
Equate h(x) = 0, hence
- 5(x + 1)(x - 9) = 0
equate each factor to zero and solve for x
x + 1 = 0 ⇒ x = - 1
x - 9 = 0 ⇒ x = 9
x > 0 hence x = 9
The object hits the ground 9 seconds after being launched