Question

Can someone get me started on this problem please, "The height of an object thrown upward with an initial velocity of 64 feet per second is given by the formula h=-16t^2 +64t, where t is the time in seconds. How long will it take the object to reach a height of 64 feet?" Thanks.

Answer 1

The problem gives you:
h=-16t^2+64t+80
where
h is height in feet
t is time in secs

Answer 2

If it hits the ground, h = 0 so
set h=0 and solve for t:
h=-16t^2+64t+80
0=-16t^2+64t+80
0=-4t^2+16t+5

Answer 3

Solving using the quadratic equation yields:
t = {-0.29, 4.29}

Answer 4

We can throw out the negative solution leaving
t = 4.29 seconds :)

Answer 5

medal plz :]

Answer 6

no, where are you getting 80?