$\"\"$

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The expression is $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$ .

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$\"\"$

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Now we prove the limit $\"\"$ using $\"\"$ definition.

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For each $\"\"$ ,there exists a $\"\"$ such that $\"\"$ whenever $\"\"$ .

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Consider $\"\"$

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$\"\"$

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Consider $\"\"$

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$\"\"$

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Observe the relationship between two absolute values $\"\"$ and $\"\"$ .

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Consider $\"\"$

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$\"\"$

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Therefore $\"\"$ .

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$\"\"$

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$\"\"$ .