A parabola intersects the x-axis at x=3 and x=9. What is the x-coordinate of the parabola's vertex?

6

Step-by-step explanation:

If the graph intersects the x-axis, then there is an x-intercept at that point. So, we know that 3 and 9 are the x-intercepts of the parabola.

Parabolas can only have 0, 1, or 2, x intercepts. The x coordinate of the vertex will be the average of the x coordinates of the x-intercepts, since the vertex will be in the middle of the 2 x intercept points.

Take the average of 3 and 9:

(3 + 9) / 2

12 / 2

= 6

The x coordinate of the vertex is 6.

step-by-step explanation:

this is not a question

answer:   28.56 feet (approx)

step-by-step explanation:

since, triangle abc has measure of angle c equal to 55 degrees, measure of angle abc equal to 90 degrees, and length of bc equal to 20 feet.

we have to find out the measurement of segment ab.

therefore, tan 55° =

but bc = 20 feet.

⇒ tan 55 ° =  

⇒ ab = 20 × tan 55 °

⇒ ab = 20 × 1.42814800674

⇒ ab = 28.5629601348   ≈ 28.56 feet