$\"\"$

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The sequence is $\"\"$ .

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$\"\"$

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To sum the terms of the arthemetic sequence use the formula : $\"\"$ .

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Here difference, $\"\"$ .

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$\"\"$

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$\"\"$ .

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$\"\"$

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Let $\"\"$ be the statement $\"\"$ .

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$\"\"$ .

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Condition 1 :

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For $\"\"$ : Because $\"\"$ is a true statement $\"\"$ is true for $\"\"$ .

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Condition 1 is satisfied.

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Condition 2 :

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Let us assume that $\"\"$ .

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$\"\"$ is true for the positive integer $\"\"$ .

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As $\"\"$ is true,then $\"\"$ must also be true.

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$\"\"$

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The final statement is excatly $\"\"$ , Therefore $\"\"$ is true.

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Condition 2 is also satisfied.

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Because $\"\"$ is true for $\"\"$ and $\"\"$ implies $\"\"$ .

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$\"\"$ is true for $\"\"$ and so on.

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By the principle of mathematical induction $\"\"$ is true for all positive integers of $\"\"$ .

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$\"\"$

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By the principle of mathematical induction $\"\"$ is true for all positive integers of $\"\"$ .