$\"\"$

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$\"\"$ is a rational function.

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Consider $\"\"$ be a rational function, $\"\"$ ,

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where $\"\"$ and $\"\"$ are the polynomials.

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Apply $\"\"$ on each side.

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$\"\"$

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Quotient rule of limits : $\"\"$ , if $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .