The directrix of the parabola `x^2-4x-8y + 12=0` is

Explanation

Equation of parabola is `x^2 - 4 x - 8y + 12 = 0`

`x^2-4x+4=8y-8`

`(x-2)^2=8(y-1)=X^2=8Y`

Comparing with `X^2=4aY`, we get `a=2`

`` Directrix is `Y=-a=>y-1=-2=>y=-1`