Step 1 :

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Limit definition of differentiation :

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$\"\"$

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For small values of $\"\"$ :

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$\"\"$

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Let $\"\"$ and $\"\"$ .

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Substitute $\"\"$ in $\"\"$ .

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$\"\"$

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Differentiate $\"\"$ with respect x.

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$\"\"$ .

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Substitute $\"\"$ in $\"\"$ .

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$\"\"$

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

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$\"\"$

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Solution :

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$\"\"$