SOLUTION: A projectile is launched into the air with an initial upward velocity of 24 feet per second. The height (h) in feet of the projectile can be modeled by h = -16t^2 + 24t + 3, where

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Question 467061: A projectile is launched into the air with an initial upward velocity of 24 feet per second. The height (h) in feet of the projectile can be modeled by h = -16t^2 + 24t + 3, where t is the time in seconds after it was launched. How much time, in seconds, does it take the object to reach 12 feet above the ground?
( TOPIC: Quadratic Equations )
Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
h(t) = -16t^2 + 24t + 3
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12 = -16t^2 + 24t + 3
-16t^2 + 24t - 9 = 0
Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
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=0 is zero! That means that there is only one solution: .
Expression can be factored:

Again, the answer is: 0.75, 0.75. Here's your graph:

t = x
t = 0.75 seconds
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