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(2a)

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The differential equation is $\"\"$ .

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The equation is in the form of linear differential equation $\"\"$ .

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Here $\"\"$ and $\"\"$ .

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Solution of first order linear differential equation $\"image\"$ is $\"image\"$ .

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$\"\"$

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Consider $\"\"$ .

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Apply integration by parts: $\"image\"$ .

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Let $\"\"$ .

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Apply derivative on each side.

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$\"\"$

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Let $\"\"$ .

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Apply integral on each side.

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$\"\"$

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$\"\"$

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Consider $\"\"$ .

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Apply integration by parts: $\"image\"$ .

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Let $\"\"$ .

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Apply derivative on each side.

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$\"\"$

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Let $\"\"$ .

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Apply integral on each side.

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$\"\"$

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$\"\"$

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Substitute above result in (2).

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$\"\"$

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$\"\"$

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Substitute above result in (1).

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$\"\"$

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$\"\"$

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Apply initial conditions $\"\"$ .

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$\"\"$

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Substitute $\"\"$ in (3).

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$\"\"$

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$\"\"$

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Partical solution of the differential equation is $\"\"$

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.