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Ex 5.2, 11 - Which term of AP 3, 15, 27, 39,... will be 132

Ex 5.2, 11 - Chapter 5 Class 10 Arithmetic Progressions - Part 2
Ex 5.2, 11 - Chapter 5 Class 10 Arithmetic Progressions - Part 3


Transcript

Ex 5.2, 11 Which term of the A.P. 3, 15, 27, 39, … will be 132 more than its 54th term? Given AP 3, 15, 27, 39,… First we need to calculate 54th term Here, a = 3 d = 15 – 3 = 12 n = 54 Putting values in formula a54 = a + (n – 1) d = 3 + (54 – 1) × 12 = 3 + 53 × 12 = 3 + 636 = 639 So, 54th term = a54 = 639 We need to calculate term which is 132 more than 54th term i.e. should be 639 + 132 Therefore, an = 771 We need to find n Putting values in formula an = a + (n – 1) d 771 = 3 + (n – 1) × 12 771 – 3 = (n – 1) × 12 768 = (n – 1) × 12 768/12 = n – 1 64 = n – 1 n – 1 = 64 n = 64 + 1 n = 65 So, 65th term is 132 more than 54th term

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.