Answer:
D. (3. —1)
Step-by-step explanation:
Vertex of a quadratic function:
Suppose we have a quadratic function in the following format:
[tex]f(x) = ax^{2} + bx + c[/tex]
It's vertex is the point [tex](x_{v}, y_{v})[/tex]
In which
[tex]x_{v} = -\frac{b}{2a}[/tex]
[tex]y_{v} = -\frac{\Delta}{4a}[/tex]
Where
[tex]\Delta = b^2-4ac[/tex]
If a<0, the vertex is a maximum point, that is, the maximum value happens at [tex]x_{v}[/tex], and it's value is [tex]y_{v}[/tex].
Turning point of a quadratic function:
The turning point of a quadratic function is the vertex.
y = x2 — 6x + 8
This means that [tex]a = 1, b = -6, c = 8[/tex]
Now, we find the vertex.
[tex]x_{v} = -\frac{b}{2a} = -\frac{-6}{2(1)} = 3[/tex]
[tex]\Delta = b^2-4ac = (-6)^2-4(1)(8) = 36 - 32 = 4[/tex]
[tex]y_{v} = -\frac{4}{4(-1)} = -1[/tex]
(x,y) = (3,-1), and the correct answer is given by option D.
