SOLUTION: An object is thrown from the top of a 144 ft building with an initial velocity of 128 ft per second. The height h of the object after t seconds is given by the quadratic equation h

Question 407925: An object is thrown from the top of a 144 ft building with an initial velocity of 128 ft per second. The height h of the object after t seconds is given by the quadratic equation h=-16t^2+128t+144/ when will the object hit the ground
Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
h=-16t^2+128t+144
.
h is height from the ground.
To find your answer set h to zero and solve for t:
0=-16t^2+128t+144
dividing both sides by -16:
0 = t^2+8t-9
factoring the right:
0 = (t-9)(t+1)
t = {-1, 9}
throw out the negative solution leaving:
t = 9 seconds
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