SOLUTION: A ball is projected into the air. Its height at time t is given by the equation h = -16t^2 + 60x +1. When will the height be 8 feet?

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Question 291689: A ball is projected into the air. Its height at time t is given by the equation h = -16t^2 + 60x +1. When will the height be 8 feet?
Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
A ball is projected into the air. Its height at time t is given by the equation h = -16t^2 + 60x +1. When will the height be 8 feet?
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When h = 8
8 = -16t^2 + 60t + 1 (I think you meant 60t, not 60x)
-16t^ + 60t - 7 = 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=3152 is greater than zero. That means that there are two solutions: .




Quadratic expression can be factored:

Again, the answer is: 0.120541394047725, 3.62945860595227. Here's your graph:

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x1 and x2 are the values of t.
There are 2 of them, 8 feet going up, and 8 feet coming back down.

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