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प्रश्न
The nth term of an A.P. 5, 8, 11, 14, ...... is 68. Find n = ?
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उत्तर
The given A.P. is 5, 8, 11, 14, ......
Here, a = 5, d = 8 – 5 = 3, tn = 68
Since tn = a + (n – 1)d,
68 = 5 + (n – 1)(3)
∴ 68 = 5 + 3n – 3
∴ 68 = 2 + 3n
∴ 66 = 3n
∴ n = `66/3`
∴ n = 22
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