Last updated at March 22, 2021 by Teachoo

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Ex 5.3, 5 The first term of an AP is 5, the last term is 45 and the sum is 400. Find the number of terms and the common difference. Given a = 5 , l = 45 & Sn = Sum = 400 Since last term is given, we can use formula Sn = ๐/๐ (a + l) Putting values in formula 400 = ๐/2 (5 + 45) 400 = ๐/2 ร 50 (400 ร 2)/50 = n 8 ร 2 = n 16 = n n = 16 So, Number of terms = 16 Finding d For d, we use the formula Sn = ๐/๐ (2a + n โ 1) d) Putting Sn = 400, n = 16, a = 5 400 = 16/2 (2 ร 5 + (16 โ 1)ร d) 400 = 8 ร (10 + 15d) 400/8 = 10 + 15d 50 = 10 + 15d 50 โ 10 = 15d 40 = 15d 40/15 = d 8/3 = d d = ๐/๐

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Ex 5.3, 5 You are here

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Ex 5.3, 15 Deleted for CBSE Board 2022 Exams

Ex 5.3, 16 Deleted for CBSE Board 2022 Exams

Ex 5.3, 17 Deleted for CBSE Board 2022 Exams

Ex 5.3, 18 Important Deleted for CBSE Board 2022 Exams

Ex 5.3, 19 Deleted for CBSE Board 2022 Exams

Ex 5.3, 20 Important Deleted for CBSE Board 2022 Exams

Chapter 5 Class 10 Arithmetic Progressions (Term 2)

Serial order wise

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Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 10 years. He provides courses for Maths and Science at Teachoo.