Hello,
[tex]The\,\,formula\,\,for\,\,the\,\,vertex\,\,of\,\,a\,\,quadratic\,\,equation\,\,is: \\ V=( -\frac{b}{2a},f(-\frac{b}{2a}) )[/tex]
That means that we must first obtain x, then we replace x in the function to get y, so:
[tex]x=- \frac{b}{2a} \\ \\ x=- \frac{8}{2*(1)} \\ \\ \boxed{x=-4} \\ \\ Reeplacing \,\,x: \\ y=(-4)^{2} +8*(-4)+12 \\ y=16-32+12 \\ \boxed{y=-4}[/tex]
Answer: V=(-4 , -4)