$\"\"$

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The diffrential equation is $\"\"$ .

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$\"\"$

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$\"\"$ .

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Integrate on both sides.

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$\"\"$ .

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$\"\"$ .

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Integration by parts : $\"\"$ .

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

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

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$\"\"$

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$\"\"$

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$\"\"$ .

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$\"\"$

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$\"\"$ .