Question

Find the sum up to 15 terms of the series √3+√75+√243+....


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Answer 1

Answer:

Rewriting the given equation, we get The given series is AP where a = √3 and d = 4√5 Now, the sum of AP is expressed as Sn = n/2[]2a + [2a + (n - 1)d] It is given that Sn = 435√3. Therefore, n/2[2a + (n - 1)d] = 435√3 Substituting the values of a and d, we get It is obvious that n = -29/2 cannot be correct value and hence the correct value is n = 15. Read more on Sarthaks.com - https://www.sarthaks.com/575382/if-the-sum-of-the-first-n-terms-of-the-series-3-75-243-507-is-4353-then-n-equals