Identifying Functions

What is the key characteristic of a relation that makes it a function?

• Every y-value is assigned to one and only one x-value.

• None of the x-values repeat.

• All x-values are positive.

• All y-values are different.

Which set of ordered pairs represents a function?

• {(-1, 3), (3, 4), (2, 6), (-2, 3)}

• {(-1, 4), (2, 4), (-1, 1), (0, 0)}

Which of the following tables represents a function?

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Which mapping diagram represents a function?

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Which graph shows a function?

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