## anonymous 3 years ago Height of a Projectile: The height of an object thrown upward from the roof of a building 408 ft tall, with an initial velocity of 96 ft/sec, is given by the equation h=-16t^2+96t+408, where h represents the height of the object after t seconds. How long will it take the object to hit the ground?

1. anonymous

when it falls on the ground what is the value of h??

2. anonymous

0

3. anonymous

so set that = 0 in the equation

4. anonymous

So it's -16t^2+96t+408=0?

5. anonymous

yes...now solve for t

6. anonymous

Can you show me the steps please?

7. anonymous

-16t^2 + 96t + 408=0 solve the quadratic equation

8. anonymous

Can you show me the steps please?

9. Mertsj

$x=\frac{-96\pm \sqrt{96^2-4(-16)(408)}}{2(-16)}$

10. Mertsj

Simplify that.