Question

After how many seconds will the ball hit the ground? h = -16t^2 + 12t + 40

Answer 1

2 seconds

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 ±
`√(b^2 - 4ac)`

x = -----------------------------

2a

where:

a = -16

b = 12

c = 40

plugin values into the formula

- 12 ±
`√(12^2 - 4 (-16) 40)`

t = ----------------------------------

2 (-16)

t = -5/4 , t = 2

therefore, the ball will hit the ground in 2 seconds