Question

if the 5th and 9th terms of a harmonic progression are 1/19 and 1/35,find the 12 term of the sequence for 11th std maths​

Answer 1

Answer:

Explanation: Now from the above HP formulae, it is clear the reciprocals of first 11 terms will make an AP. The sum of first 11 terms of an AP = [2a + (11 – 1) d] 11/2 = 110

⇒ 2a + 10d = 20 ⇒ a + 5d = 10

Now there are 2 variables, but a + 5d = T6 in an AP series. And reciprocal of 6th term of AP series will give the 6th term of corresponding HP series. So, the 6th term of HP series is 1/10

Step-by-step explanation:

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