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The function is

\"\"

.

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Apply derivative on each side with respect to

\"\"

.

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\"\"

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The sign changes of $\"\"$ :

\

\"\"

on

\"\"

.

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\"\"

on

\"\"

.

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$\"\"$ on $\"\"$ .

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$\"\"$

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$\"\"$ on $\"\"$ .

\ Therefore

\"\"

.

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$\"\"$ .

\