Arock falls to the ground 400 feet below, the distance the rock falls in t seconds is given by the equation d(t)=-16t to the power of 2 +400 how long does it take for the rock to hit the ground

the distance the rock has to travel to hit the ground is 400ft.  

400 = 16 * t^2divide both sides by 16 and take the square root.  

25=t^2

5=t

is there any attachment? what are the equations?

correct answer:

i^31 = -i