The function 2 ft t t ( ) 5 20 60    models the approximate height of an object t seconds after it is launched. how many seconds does it take the object to hit the ground?

The function involves the initial speed of the object, and the height
from which it was launched, and whether it was launched upward
or downward.  As you can see, your post was corrupted and is
unreadable.  But when the object hits the ground, its height is zero. 
Set the function equal to zero, solve the quadratic equation that you
have, discard the negative solution, and the positive solution is your
answer.