SOLUTION: A professional stunt diver jumps off a tower. His height above the ground is given by the expression h(t)=-5t^2+20. How long does it take for the diver to reach the water?

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Question 951227: A professional stunt diver jumps off a tower. His height above the ground is given by the expression h(t)=-5t^2+20. How long does it take for the diver to reach the water?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
A professional stunt diver jumps off a tower.
His height above the ground is given by the expression h(t)=-5t^2+20.
How long does it take for the diver to reach the water?
:
When he strikes the water his height is 0, therefore
-5t^2 + 20t = 0
simplify, divide by -5t
t - 4 = 0
t = 4 seconds