$\"\"$

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(a)

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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 chain rule of derivative : $\"\"$ .

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$\"\"$ .

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$\"\"$ .

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If $\"\"$ is a function , which is differentiable and $\"\"$ is an independent variable,

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then the differential $\"\"$ in terms of $\"\"$ is defined as $\"\"$ .

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$\"\"$ .

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$\"\"$

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(b)

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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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$\"\"$

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$\"\"$

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$\"\"$

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Differential of the function is $\"\"$ .

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$\"\"$

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(a) $\"\"$ .

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(b) $\"\"$ .