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20 votes
20 votes
I have two hours to get this done please help me I’ve been stuck on this problem

I have two hours to get this done please help me I’ve been stuck on this problem-example-1
User Ildjarn
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1 Answer

21 votes
21 votes

Answer:

The answers are all bolded below. If you can, please read the explanation so you can pass a test if asked.

Explanation:

First, the quadratic equation we are starting with is -x^2 + 10x + 9.5

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For the first part, it's asking for how high it is when it starts, commonly, we use 0 as the start point so if we plug 0 into the quadratic equation, we have 9.5. The height is 9.5 feet at start.

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For the second part I'm assuming it's asking for either a minimum or a maximum and because the equation has a -x^2, that means the parabola has a maximum. You can tell by -x^2 being negative, if it was x^2 (positive) it would have a minimum.

The maximum is found using the vertex formula(because the vertex is the max or min), -b/2a, where a is -1, b is 10, and c is 9.5 found in the equation because the quadratic is in standard form ax^2 + bx + c. This gives a vertex of 5.

We plug 5 back in the equation to get (5, 34.5).

5 is the x-coordinate so it is 5 feet horizontally and 34.5 feet high

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For the last part it's asking for a root, or when the parabola touches the x axis/the ground.

-x^2 + 10x + 9.5

You would use the quadratic formula but I'm too lazy so I just put it into a calculator.

That gives roots of around x=−0.87367 and x=10.8737.

You can't have a negative root so you're left with x= 10.8737, rounding to the tenth decimal place, 10.9.

I think that's correct, could be wrong, if it is wrong just follow the steps and it should be fine.

User Bilal Ali Jafri
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3.1k points