Can you make the answer clearer. I would be glad to help you. I just don't understand where it says "the sum of three numbers is 16 the sum of twice the first number"
Four plus a number times three is seventeen
The vertex of the given parabola is the point (3, 25).
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How to get the vertex of the parabola?</h3>
If the parabola has roots x₁ and x₂, then the vertex of the parabola is at:
xₙ = (x₁ + x₂)/2
Here the parabola is:
y = (-2 - x)*(x - 8)
We can rewrite that to:
y = -(x + 2)*(x - 8)
Then the two roots are:
x = -2 and x = 8
Then the vertex is at:
xₙ = (8 - 2)/2 = 6/2 = 3
To get the y-value of the vertex, we evaluate the equation in x = 3:
y = -(3+ 2)*(3 - 8) = -5*(-5) = 25
The vertex is (3, 25).
If you want to learn more about parabolas:
brainly.com/question/4061870
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Answer:

Step-by-step explanation:




