SOLUTION: Tossing a Ball. A ball is tossed into the air at 10ft/sec from a height of 5 feet. How long does it take to reach the ground? I really don't know even how to set this problem

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Question 192275This question is from textbook
: Tossing a Ball. A ball is tossed into the air at 10ft/sec from a height of 5 feet. How long does it take to reach the ground?
I really don't know even how to set this problem up. I just need the formula, and then I'm able to figure it out!! This question is from textbook

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
A ball is tossed into the air at 10ft/sec from a height of 5 feet. How long does it take to reach the ground?
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h(t) = -16t^2 + 10t + 5 --- h is the height at any time t (in seconds)
Find t when h = 0
16t^2 - 10t - 5 = 0
Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 16x%5E2%2B-10x%2B-5+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%28-10%29%5E2-4%2A16%2A-5=420.

Discriminant d=420 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--10%2B-sqrt%28+420+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-10%29%2Bsqrt%28+420+%29%29%2F2%5C16+=+0.952934422872475
x%5B2%5D+=+%28-%28-10%29-sqrt%28+420+%29%29%2F2%5C16+=+-0.327934422872475

Quadratic expression 16x%5E2%2B-10x%2B-5 can be factored:
16x%5E2%2B-10x%2B-5+=+%28x-0.952934422872475%29%2A%28x--0.327934422872475%29
Again, the answer is: 0.952934422872475, -0.327934422872475. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+16%2Ax%5E2%2B-10%2Ax%2B-5+%29

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Sub x for t
Use the positive answer,
t = 0.9529344... seconds