What is the vertex of this parabola y=-4x^2+8x-12

The answer you are looking for is (1, - 8)

remember that: x=[ (-b/2a) ]

and that the problem is set up as y=ax^2+bx+c

calculate:

x=[-8/2 (-4) ]

x=[-8/-8]

x=1

then:

y = (-4) * 1^2 + (8*1) - 12

y = (-4) + 8-12

y = (-4) + 8-12

y=4-12

y = (-8)

(1, - 8)