$\"\"$

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The derivative is $\"\"$ at $\"\"$ , $\"\"$ and $\"\"$ .

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$\"\"$ .

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$\"\"$ .

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$\"\"$ .

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Therefore $\"\"$ .

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$\"\"$

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Therefore $\"\"$ .

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$\"\"$

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Graph :

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Graph the function $\"\"$ .

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$\"\"$ .

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$\"\"$

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The function is $\"\"$ .

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Graph:

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$\"\"$ .