You can
put this solution on YOUR website!s(t)=-16(t^2)+142t
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In this case, they are saying that if s(t) equals 172 feet what is t?
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Simply set s(t) to 172 and solve for 't':
s(t)=-16(t^2)+142t
172=-16(t^2)+142t
16(t^2)-142t+172=0
8(t^2)-71t+86=0
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Since it is difficult to factor, we use the quadratic equation.
Doing so will yield:
x = {7.428, 1.447}
Units are in seconds
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Here's the quadratic equation:
| 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=2289 is greater than zero. That means that there are two solutions:  .
Quadratic expression  can be factored:
Again, the answer is: 7.42771842847642, 1.44728157152358.
Here's your graph:
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