The height of a projectile in feet at time t is determined by the equation h=-16t^2+128t+320. At what time will the projectile be 560 feet high

At 3 seconds and again at 5 seconds

Step-by-step explanation:

h = - 16t² + 128t + 320

560 = - 16t² + 128t + 320

16t² - 128t + 240 = 0

t² - 8t + 15 = 0

t² - 5t - 3t + 15 = 0

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

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

t = 3, t = 5

3 seconds and 5 seconds

Step-by-step explanation:

Let the function equal 560 ft

560=-16t^2+128t+320

Subtract 560 from each side

560-560=-16t^2+128t+320-560

0 = -16t^2+128t-240

Divide each side by - 16

0/-16 = (-16t^2+128t-240) / -16

0 = t^2 - 8t-15

Factor

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

Using the zero product property

t-5 = 0 t-3=0

t=5 t=3