Find the sum : 7 +10(1/2) + 14 +......+ 84.

Question

KnowledgeBoat · Accepted Answer

Series : 7 + 10.5 + 14 + ....... + 84 The above series is an A.P. with common difference = 3.5 Let 84 be nth term in the A.P. We know that, ∴ an = a + (n - 1)d ⇒ 84 = 7 + (n - 1) × 3.5 ⇒ 84 - 7 = (n - 1) × 3.5 ⇒ 77 = (n - 1) × 3.5 ⇒ = (n - 1) ⇒ 22 = (n - 1) ⇒ n = 22 + 1 ⇒ n = 23. We know that, Sum of n terms of an A.P. is given by, ∴ Sn = (a + l) ⇒ S23 = (7 + 84) = (91) = Hence, S23 = .

Mathematics

Find the sum : 7 +10(1/2) + 14 +......+ 84.

AP

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Mathematics

Find the sum : 7 +10(1/2) + 14 +......+ 84.

AP

Related Questions

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