$\"\"$

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The function is $\"\"$ .

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Apply derivative with respect to x .

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$\"\"$

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Apply difference rule of derivatives : $\"\"$ .

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$\"\"$

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Derivative of absolute function : $\"\"$ .

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$\"\"$

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$\"\"$

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Find the derivative at extremum :

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The derivative at a point $\"\"$ is

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$\"\"$

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$\"\"$ is undefined.

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$\"\"$

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$\"\"$ is undefined.