Y = - 3x2 - 12

Axis of symmetry:

The answer to that would be - 18

Answer: x = 0

Work Shown:

y = - 3x^2 - 12 is the same as y = - 3x^2 + 0x + (-12)

Compare this to y = ax^2 + bx + c, and we'll find that

a = - 3

b = 0

c = - 12

Plug the 'a' and 'b' values into the formula below and simplify

h = - b / (2a)

h = - 0 / (2 * (-3))

h = 0

The x coordinate of the vertex is x = 0, so the axis of symmetry is also x = 0.

The axis of symmetry lays perfectly on top of the y axis.