Answer:
-18
Step-by-step explanation:
First, to find the y coordinate of the vertex, we need to find the x coordinate of the vertex.
The vertex will always be in the middle of the roots of the quadratic. The roots of the polynomial are 3 and 9, so the x coordinate of the vertex will be (3+9)/2 = 6.
Now that we know the x coordinate of the vertex, we can just plug in 6 for x to find the y coordinate:
2(6-3)(6-9)
=2(3)(-3)
=-18
