$\"\"$

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The function is $\"\"$ .

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Apply first derivative on each side.

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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Apply second derivative on each side.

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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Apply second derivative on each side.

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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Apply fourth derivative on each side.

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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Rewrite the above equation.

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$\"\"$

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

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$\"\"$

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Hence the function $\"\"$ is a solution of differential equation $\"\"$ .

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$\"\"$

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The function $\"\"$ is a solution of differential equation $\"\"$ .