The series is $\"\"$

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Here $\"\"$

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$\"\"$

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So, the series is in Arithmetic progression.

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First term $\"\"$ , common difference $\"\"$

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Formula for $\"\"$ term in AP series is $\"\"$ .

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$\"\"$ term in AP series is $\"\"$

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$\"\"$

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Formula for sum of first n terms is $\"\"$

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Sum of first 5 terms is

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$\"\"$

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$\"\"$ $\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ $\"\"$

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$\"\"$

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$\"\"$ $\"\"$

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$\"\"$

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The sum of the first 6 terms is $\"\"$