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  1. The 1st term of an HP is 1/17 and the product of the 2nd and 4th term equals to the products of 5th and 6th term of the HP. Find the 3rd term of the HP. ?
    1. 1/7
    2. 1/14
    3. 1/35
    4. None of these
Correct Option: A

The 1st term of an HP is 1/17 .
Hence, for the corresponding AP, the terms is 17 .
Here, a = 17
nth term of an AP is given by Tn = a + (n -1)d
∴ T2 = 17 + d, T4 = 17 + 3d
T5 = 17 + 4d, T6 = 17 + 5d
∴ (17 + d) (17 + 3d) = (17 + 4d) (17 + 5d)
⇒ 289 + 51d + 17d + 3d2 = 289 + 85d + 68d + 20d2
⇒ 68d + 3d2 = 153d + 20d2
⇒ 17d2 = -85d
⇒ d = -5
∴ 3rd term is T3 = a + 2d = 17 + 2(-5)
= 17 - 10 = 7
Hence, for the corresponding HP, the 3rd term is 1/7.



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