A scientist launched an object upward at a speed of 32 ft per second from a height of 240 feet. The height of the object is modeled by the equation h = 240 + 32t - 16t2. After how much time will the object hit the ground? A 3 seconds B 5 seconds C 12 seconds D 20 seconds

B 5 seconds

Step-by-step explanation:

h = 240 + 32t - 16t^2

When is this equation 0

0 = 240 + 32t - 16t^2

Factor out 16

0 = - 16 (-15-2t+t^2)

= - 16 (t^2-2t-15)

What 2 numbers multiply to - 15 and add to - 2

-5*3 = - 15

-5+3 = -2

0 = - 16 (t-5) (t+3)

Using the zero product property

t-5=0 t+3=0

t=5 t=-3

Since time cannot be negative

t=5 seconds