Hadi B. answered • 04/03/19

BS in Mathematics with 5+ years of tutoring experience

the object will hit the ground when the height is 0, or when h(x) = 0

set h(x) equal to 0, 0 = -5(x + 1)(x - 9)

h(x) = 0 when x = -1 and when x = 9

-1 seconds before the object is launched doesn't make sense

9 is the answer that makes sense, so the object hits the ground after 9 seconds