\"\"

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The equation is \"\".

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The equation tells us to take an input \"\" and squaring.

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For any input of \"\", we get only one output for \"\".

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\"\"

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An input \"\".

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Substitute \"\" in \"\".

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\"\"

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\"\".

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An input \"\".

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Substitute \"\" in \"\".

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\"\"

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\"\".

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For any input of \"\", we get only one output for \"\".

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So, the equation \"\" defines \"\" as a function of \"\".

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\"\"

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The equation \"\" defines \"\" as a function of \"\".