Answer:
No
Step-by-step explanation:
The definition of a function is in general:
For each x value there is exactly one y value.
This is not true for your given equation:
For example the x-value: 0 gives y^2 = -12 which has no real solution (but two imaginary solutions)
For example the x-value: -3 gives y^2 = 3 which has the solutions y = [tex]\sqrt{3}[/tex] and y = - [tex]\sqrt{3}[/tex]
Therefore the "exactly one y value" rule is almost everywhere not fulfilled, therefore the horizontal parabola y^2 = -5x -12 is not a function.