Answer:
The vertex is the point (1,-8)
Explanation:
we have

Convert to vertex form
step 1
Group terms that contain the same variable, and move the constant to the opposite side of the equation

step 2
Factor the leading coefficient
factor -4

step 2
Complete the square. Remember to balance the equation by adding the same constants to each side


step 3
Rewrite as perfect squares

therefore
The vertex is the point (1,-8)