Question 309225
    The height (h) of a baseball (t) seconds after being hit is given by h(t)= -16t^2 + 80t + 9. 
What is the height of the baseball when it is into the air? 
The height is given by the equation:
h(t)= -16t^2 + 80t + 9
where
h(t) is the height 
t is time in seconds
.
What is the maximum height of the baseball and when does it reach this height? 
Maximum height is at the vertex:
t = -b/(2a) =  -80/(2*(-16)) = 80/32 =  2.5
h(2.5) =  -16(2.5^2) + 80(2.5) + 9 = 109 feet
When does the baseball hit the ground?
set h(t) to zero solve for t:
0 = -16t^2 + 80t + 9
Solve using the quadratic formula to get:
t = {-0.11, 5.11}
Throw out the negative solution leaving:
t = 5.11 secs
.
Details of quadratic :
*[invoke quadratic "x", -16, 80, 9 ]