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Ex 5.3, 3 - Chapter 5 Class 10 Arithmetic Progressions - Part 3

Ex 5.3, 3 - Chapter 5 Class 10 Arithmetic Progressions - Part 4

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Ex 5.3, 3 In an AP (ii) Given a = 7, a13 = 35, find d and S13. Given a = 7, a13 = 35 We need to find d We know that an = a + (n – 1) d Putting a = 7, n = 13 and an = 35 35 = 7 + (13 – 1) Γ— 𝑑 35 = 7 + 12d 35 – 7 = 12d 28 = 12 d 28/12=𝑑 7/3=𝑑 d = πŸ•/πŸ‘ Now we need to find S13 We can use formula Sn = 𝒏/𝟐 (𝒂+𝒍) Putting n = 13, a = 7, 𝑙 = a13 = 35 = 13/2(7+35) = 13/2 Γ— 42 = 13 Γ— 21 = 273

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.