Answer:
All answers in this set can be written in the form y=f(x).
First we have to find the vertex (h,k) h is also x and it also is the a xis symmetry
1st: group the number
(X2+6x)-9
2nd: use b/2
6/2 = 3 , 3^2= 9
(X2+6x+9)-9-9
(X2 + 3)-18
Vertex is 3,-18 so the symmetry is 3
