h(x)=−5(x+1)(x−9) How many seconds after launch will the object hit the ground?

Answer 1

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