The vertex is the minimum or the maximum point of the parabola.
<em>x and f(x) represent the horizontal and the vertical coordinates of the vertex.</em>
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The standard form of a parabola is

The x coordinate of the parabola is calculated using:

The value of the x-coordinate is then plugged in, into the equation to calculate the y-coordinate, as follows:

At the end of the calculation,
x and f(x) represent the horizontal and the vertical coordinates of the vertex.
Take for instance:

The x-coordinate of the vertex is:




The y-coordinate is:



So, the vertex of
is (-1,11)
See attachment for illustration of vertex of 
Read more about vertex of parabola at:
brainly.com/question/20209326