Which is the equation of a parabola with vertex (0, 0), that opens to the left and has a focal width of 12?

Step-by-step explanation:

We need to find the equation of parabola using given information

If parabola open left and passes through origin then equation is

Focal width = 12

Focal width passes through focus and focus is mid point of focal width.

Focus of above parabola would be (-a,0)

Passing point on parabola (-a,6) and (-a,-6)

Now we put passing point into equation and solve for a

a can't be negative.

Therefore, a=3

Focus: (-3,0)

Equation of parabola:

Please see the attachment of parabola.