can you help me slove this

Question

A man throws a ball almost straight up from the edge of a
64-foot cliff. If the balls leaves his hand with a speed of
48 feet per second, its height at time
t is given by
h=-16t2+48t+64, measured from the ground below the cliff.

 

when will the ball land on the grown below the cliff

Answer 1

h(t) = -16t² + 48t + 64

 

The ball reaches the ground when h(t) = 0.  Solve the quadratic 

 

-16t² + 48t + 64 = 0.

 

You will obtain two solutions.  One will be negative, which you reject since time is positive from the moment the ball is launched.  The other solution will be positive.  That is the time when the ball reaches the ground on the way down.  Feel free to post a comment if you need further help.