$\"\"$

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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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$\"\"$ .

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$\"\"$ .

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Apply second 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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$\"\"$

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The differential equation is $\"\"$ .

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Substitute $\"\"$ and $\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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Therefore, the values of $\"\"$ are $\"\"$ .

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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 respect to $\"\"$ .

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$\"\"$

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

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$\"\"$

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$\"\"$

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$\"\"$

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Apply second 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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$\"\"$

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Substitute $\"\"$ .

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$\"\"$

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Subtract $\"\"$ .

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$\"\"$

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Therefore, $\"\"$ .

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$\"\"$ is also a solution of $\"\"$ .

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$\"\"$

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(a) The values of $\"\"$ are $\"\"$ .

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(b) $\"\"$ is also a solution of $\"\"$ .