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The sum of the 2nd and the 7th terms of an AP is 30. If its 15th term is 1 less than twice its 8th term, find the AP.

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Correct Answer - 1, 5, 9, 13,…
`T_(2) + T_(7) = 30 rArr (a+d) + (a+6d) = 30 rArr 2a + 17d = 30. " "…(i)`
`T_(15) = 2T_(8)-1 rArr (a+14d) = 2(a+7d) -1 rArr a = 1.`
Putting a = 1 (i), we get d = 4.

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