Ex 5.2, 4 - Which term of AP 3, 8, 13, 18, ... is 78? - Ex 5.2

Ex 5.2, 4 - Chapter 5 Class 10 Arithmetic Progressions - Part 2

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Ex 5.2, 4 Which term of the A.P. 3, 8, 13, 18, … is 78? Given AP 3, 8, 13,18, … We need to find which term is 78 Hence, an = 78 a = 3 d = 8 – 3 = 5 Putting these in formula an = a + (n – 1) d Putting values 78 = 3 + (n – 1) × 5 78 – 3 = (n – 1) × 5 75 = (n – 1) × 5 75/5 = (n –1) 15 = n – 1 n – 1 = 15 n = 15 + 1 n = 16 So, the 16th term of A.P. is 78

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo