The sum of the first 9 terms of an A.P is 81 and the sum of it's f | Filo
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Class 10

Math

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Sequences and Series

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The sum of the first terms of an is and the sum of it's first terms is Find the first term, the common difference and the sum upto term.

  1. None of these
Correct Answer: Option(d)
Solution: Sum of the term
Given sum of terms

Sum of terms





Multiply eq by and and eq by and subtract both the equation




Now substitute the in eq




Sum of the 15th Term





Hence



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