$\"\"$

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The function is $\"\"$ , then $\"\"$

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Substitute $\"\"$ in the function $\"\"$ .

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$\"\"$

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Substitute $\"\"$ in the function $\"\"$ .

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$\"\"$

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Consider $\"\"$ .

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$\"\"$

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If the function is $\"\"$ then $\"\"$ .

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The stament is true.

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$\"\"$

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$\"\"$ is true for all values of $\"\"$ .