SOLUTION: An arrow is shot into the air is 144t - 4.9t2 meters above the ground t seconds after it is released. During what period(s) of time is the arrow above 68.6 meters? Round your answe

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Question 876037: An arrow is shot into the air is 144t - 4.9t2 meters above the ground t seconds after it is released. During what period(s) of time is the arrow above 68.6 meters? Round your answer to the nearest .01 second.
Answer by ewatrrr(24785)   (Show Source): You can put this solution on YOUR website!
t = .48sec and
68.6 = -4.9t^2 + 144t
-4.9t^2 + 144t - 68.6 = 0
t = .48 and t = 28.90
from t = .48sec to 28.90sec
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation (in our case ) has the following solutons:



For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

Discriminant d=19391.44 is greater than zero. That means that there are two solutions: .




Quadratic expression can be factored:

Again, the answer is: 0.484372370178204, 28.9033827318626. Here's your graph:
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