Hello,
We have to use this relation : 
He we have :

Here we are given the x intercepts at x=3 and x=9
So let us try to make quadratic equation for this using given information.
We have factors in the form (x-a)(x-b)
where a and b are x intercepts given to us.
So rewriting in factored form:

Now let us simplify it:

Let us find the vertex now,
For a quadratic equation of the form:

For x coordinate , we have the formula,

So using this formula for our equation,

So x = 6
Answer: The x-coordinate of the parabola's vertex is 6.
Answer:
Step-by-step explanation:8 inches
89 is the answe 89
Answer:
0, 16
1, 15
2, 14
3, 13
4, 12
5, 11
6, 10
7, 9
8, 8
Step-by-step explanation:
Any two numbers that have the product of positive 16 have a geometric mean of 4.