An explosion causes debris to rise vertically. the formula h=-16t^2+48t describes the height of the debris above the ground, h, in feet, t seconds after the explosion. when will the debris be 32 feet above the ground?

To get the result we have to subsitute h=32 to given equation and solve it.
32=-16t^2+48t       /-32
0=-16t^2+48t-32   /*(-1)
0=16t^2-48t+32    /:4
4t^2-12t+8=0       /:4
t^2-3t+2=0
Now we can use delta
delta=b^2-4ac
delta=9-4*2=1
x1=
x2=
The answer is 1 second and 2 second (when hover and falling down)