Samantha M. answered • 12/01/16
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For an equation to represent a function, every value of x in the domain can be mapped to one and only one value of y.
The easiest way to think of this when you're just starting out is to graph the function on a coordinate plane, and then use the "vertical line test" to figure out if there are any x-values that have more than one y-value.
http://www.mathwords.com/v/vertical_line_test.htm
If you can draw a vertical line on the graph and it passes through two or more points, it's not a function
If there is no vertical line that could pass through two points, it is a function. This link above is an example.
https://www.wolframalpha.com/ This is a website you can use to graph that equation. You'll find that it is a function
