Step-by-step explanation:
h = b/2a
h= -12/2(-2)
h= -12/-4
h= 3
k = 4ac - b^2/ 4a
k = 4(-2)(-7) - (-12)^2/ 4(-2)
k = 56 - 144 / -8
k = -88 / -8
k = 11
y = -2x^2 - 12x - 7 in the form a(x-h)^2 + k
= -2(x + 3)^2 + 11
vertex = (h,k)
therefore the vertex is 3 and 11