Answer:
First part = 2.
Time to land = 6 seconds.
Step-by-step explanation:
The object is at h = 0 when it land so
-5x^2 + 20x + 60 = 0
-5(x^2 - 4x) = -60
-5[(x - 2)^2 - 4] = -60
(x - 2)^2 - 4 = -60/-5 = 12
(x - 2)^2 = 16.
Solving the above:
Take the square root of both sides:
x - 2 = 4
x = 2 + 4
x = 6 seconds
