Question

When given a graph, the vertical line test can be used to determine functionality. Describe the vertical line test and explain the reasons why a graph would, or would not, represent a function.

Answer 1

Explanation:

vertical line test: a test that uses any kind of straight stuff (i.e line, pen, etc.) to go over the graph and check whether or not there are two points on one vertical line.

In a function, one domain (x value) can only have one range (y value).

NOTE: one range can have multiple domains

This means through vertical line test, if there are two points on one vertical line, it will not be a function.

Answer 2

Explanation:

You are given a graph and wish to determine whether or not it represents a function. Draw a vertical line through this graph and count the number of times the vertical line intersects the graph.

If exactly once, the graph passes the vertical line test and we say the graph represents a function.

If more than once, the graph fails the test and does not represent a function.

This is because a function assigns one and only one y value to any input value x in the domain.