Functions can be described in multiple ways.

• by an equation

• input-output table

• using words

• by a graph

• as a set of ordered pairs​​

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​We know that the graph to the right is a function. What other way is this function being described?

​Describing a function.

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Remember: a function has EXACTLY ONE output for every input. An input(x) cannot have two different outputs(y)

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Identifying Functions

Does each input(x) have EXACTLY ONE output(y)?

Is this a function?

Does each number on the x-axis have EXACTLY ONE point above it?​

Is this a function?

(-2, 5), (-1, 8), (0, 6), (1, 6), (2, 7)

(-2, 0), (-1, 0), (-1, 1), (0, 1), (1, 2), (2, 2)

Each radio frequency x in a listening area has exactly one radio station y.

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The same television station can be found on more than one channel y.​

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​Are these functions?

x = 2

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y = 2x + 3​

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​Are these functions?