Answer:
Vertex is (-8, 4) not one of the answers offered!
Step-by-step explanation:
Factor -1/8 out of the first two terms. Leave a space inside parentheses in which to add a number.
[tex]y=-\frac{1}{8}(x^2 + 16x + \text{-----})-4[/tex]
Complete the square by squaring half the coefficient of x and adding it in the space.
[tex](\frac{16}{2})^2=64[/tex]
Add 64 in the space you made, then compensate for that at the end of the expression by subtracting [tex]-\frac{1}{8}(64)=-8[/tex]
[tex]y=-\frac{1}{8}(x^2+16x+64)-4+8\\y=-\frac{1}{8}(x+8)^2+4[/tex]
The x-coordinate of the vertex is the opposite of +8, the number inside the parentheses. The y-coordinate of the vertex is the number at the end of the expression.
V(-8, 4)
