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: 
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