$\"\"$

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$\"\"$ , $\"\"$ and $\"\"$ .

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Find the value of $\"\"$ .

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Formula for $\"\"$ term of arithmetic sequence is $\"\"$ .

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Substitute $\"\"$ , $\"\"$ and $\"\"$ in $\"\"$ term.

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$\"\"$

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$\"\"$

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$\"\"$ .

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$\"\"$

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$\"\"$ .