$\"\"$

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The function is $\"\"$ .

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(a).

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Find the continuity of $\"\"$ at $\"\"$ .

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$\"\"$ continuous at $\"\"$ , Since $\"\"$ .

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$\"\"$

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(b).

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$\"\"$ .

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Apply derivative on each side with respect to $\"\"$ .

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$\"\"$

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$\"\"$

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The product rule of derivative : $\"\"$ .

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$\"\"$ then $\"\"$ .

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$\"\"$ then

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$\"\"$

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$\"\"$

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$\"\"$

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

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$\"\"$

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$\"\"$

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Therefore $\"\"$ is differentiable at $\"\"$ .

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$\"\"$

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(a). $\"\"$ continuous at $\"\"$ .

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(b). $\"\"$ is differentiable at $\"\"$ .