Answer:
The vertex is (-2, -11 ).
Step-by-step explanation:
Here, the given equation is,
-----(1)
Which is a parabola along x-axis,
Since, the standard form of parabola along x-axis is,

Where (h,k) is the vertex of the parabola,
By solving it,
-----(2),
By comparing equation (1) and (2),
We get,
a = 2, -2ah = 8 and ah² + k = - 3
⇒ -2(2) h = 8 ⇒ - 4 h = 8 ⇒ h = -2
And, (2)(-2)² + k = - 3
⇒ 8 + k = - 3
⇒ k = -11
Hence, the vertex of the given equation is (-2, -11 )