A parabola is a mirror-symmetrical U-shape.
- The equation of the parabola is

- The focus is

- The directrix is

- The axis of the symmetry of parabola is:

From the question, we have:


The equation of a parabola is:

Substitute the values of origin and vertex in 



Collect like terms

Solve for a

Substitute the values of a and the vertex in 

The focus of a parabola is:

Substitute the values of a and the vertex in 




The equation of the directrix is:

So, we have:
----- the directrix
The axis of symmetry is:

We have:

Expand

Expand


A quadratic function is represented as:

So, we have:


Recall that:

So, we have:


This gives


Hence, the axis of the symmetry of parabola is: 
Read more about parabola at:
brainly.com/question/21685473
f(-9) means x is -9
Replace x with -9 and solve:
2/3(-9) - 6
Simplify:
-6 - 6 = -12
f(-9) = -12
Answer:
Step-by-step explanation:
Given that angle A is in IV quadrant
So A/2 would be in II quadrant.
sin A = -1/3
cos A = 
(cos A is positive since in IV quadrant)
Using this we can find cos A/2

Answer:
$1.25
Step-by-step explanation:
90 / 72 = the cost per student
90 / 72 = 1.25