To determine whether a graph of a relation is also a function, Shayla declares that the y-axis is a vertical line and counts the
number of times that the graph intersects the y-axis. If the graph has exactly one y-intercept, Shayla concludes that the graph shows a function. In all other cases, she declares that it is not a function. Is Shayla applying the vertical line test correctly?
The function is any equivalence relation in which there is only one output for every input. This means that the domain must be exhausted in order to gain all the elements of the range and each element of domain gets mapped to only one of the elements of the range. Vertical line test is used to determine whether a graph is a function or not. This test requires that vertical lines parallel to y-axis and including y-axis be drawn on the graph to see that each vertical line intersects the graph only once. This must be true for all the elements of the domain. Therefore, vertical line test requires to draw numerous vertical lines other than the y-axis since the definition of the function requires that. In short, mathematically, there will be a need for infinite number of vertical lines to perform the test. Therefore, Shayla is not applying the vertical line test correctly!!!
