The function y = -16t^2 + 486 models the height y in feet of a stone t seconds after it is dropped from the edge of a vertical cliff. How long will it take the stone to hit the ground? Round to the nearest hundredth of a second.

Question

The function y = -16t^2 + 486  models the height y in feet of a stone t seconds after it is dropped from the edge of a vertical cliff. How long will it take the stone to hit the ground? Round to the nearest hundredth of a second.

anonymous · Answer

I like your profile. I wish I can help you with this but I'm not good @ math

anonymous · Answer

lol it's okay

anonymous · Answer

@ganeshie8 @wolf1728

wolf1728 · Answer

height =  -16t^2 + 486 
we need the time when height = zero 
time² = (height -486) / -16
time = sq root [(0 -486) / -16]
time = sq root (-486 / -16)
time = sq root (30.375)
time = 5.5113519213 seconds
time = 5.51 seconds

anonymous · Answer

I'm sorry my laptop was updating.. Thank you @wolf1728