You need to determine where the vertex of quadratic function is located, with respect to x and y axis.
You also may determine the vertex using derivative of the function, such that:
`f'(x) = (x^2-8x+16)' => f'(x) = 2x - 8`
The x coordinate of vertex is the solution to equation `f'(x) = 0` , such that:
`2x - 8 = 0 => 2x = 8 => x = 8/2 => x = 4`
You may determine y coordinate of vertex, replacing 4 for x in quadratic equation of `f(x)` , such that:
`f(4) = 4^2-8*4+16 => f(4) = 16 - 32 + 16 => f(4) = 0`
You should notice that the graph of the function `f(x) = x^2-8x+16` is tangent to x axis at `x = 4` .
To find out the place the vertex of the parabola f(x) = y is, we'll have to identify the quadrant or the side of x axis where the coordinates of the vertex of the graph of parabola lie.
We'll recall that the coordinates of the parabola vertex are:
V(-b/2a;-delta/4a), where a,b,c are the coefficients of the function and delta=b^2 -4*a*c.
y=f(x)=x^2 - 8x + 16
We'll identify the coefficients:
a=1, 2a=2, 4a=4
delta =64 - 64
delta = 0
Since the x coordinate is positive and y coordinate is 0, the vertex is located on the positive side of x axis: V(4;0).