SOLUTION: A rock is thrown upward with a velocity of 21 meters per second from the top of a 48 meter high cliff, and it misses the cliff on the way back down. When will the rock be 7 meters

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Question 1164239: A rock is thrown upward with a velocity of 21 meters per second from the top of a 48 meter high cliff, and it misses the cliff on the way back down. When will the rock be 7 meters from ground level? Round your answer to two decimal places.
using 9.8
Answer by Alan3354(69443) About Me  (Show Source):
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A rock is thrown upward with a velocity of 21 meters per second from the top of a 48 meter high cliff, and it misses the cliff on the way back down. When will the rock be 7 meters from ground level? Round your answer to two decimal places.
using 9.8
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Its vertical position is
h(t) = -4.9t^2 + 21t + 48
-4.9t^2 + 21t + 48 = 7
Solve for t