An example of a not function is x = a; where x = 2 and a = 2
A Vertical Line disobeys the definition of a function so it is not a function
A Function is a reference between domain and range such that each value in the domain resembles only one value in the range.
Vertical line feature at least one value in the domain that compares to two or more values in the range.
A vertical line is not a function because its domain is the x-intercept, and its range is all actual numbers.
The equation for a vertical line has the form x = a, where a is the x-intercept.
The slope is absent in Vertical lines.
A vertical line that's not the y-axis has no intercept whereas a vertical line that is the y-axis has an endless number of y-intercepts.