Answer:
2 seconds
Step-by-step explanation:
h = -16t^2 + 12t + 40
by the time the ball hit the ground, height (h) = 0
0 = -16t^2 + 12t + 40
solve time (t) using quadratic equation: ax^2+bx+c=0
- b ± [tex]\sqrt{b^2 - 4ac}[/tex]
x = -----------------------------
2a
where:
a = -16
b = 12
c = 40
plugin values into the formula
- 12 ± [tex]\sqrt{12^2 - 4 (-16) 40}[/tex]
t = ----------------------------------
2 (-16)
t = -5/4 , t = 2
therefore, the ball will hit the ground in 2 seconds
