$\"\"$

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The equation is $\"\"$ .

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Take logarithm on each side.

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$\"\"$

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Apply power property of logarithm : $\"\"$ .

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$\"\"$

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Property of inverse logarithm : $\"\"$ .

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$\"\"$

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Change of base formula : $\"\"$ .

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$\"\"$

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Differentiate with respect to $\"\"$ .

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$\"\"$

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Substitute $\"\"$ in the above equation.

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$\"\"$ .

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$\"\"$

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$\"\"$ .