Ex 5.2, 15 - For what value of n, are nth terms of two APs

Ex 5.2, 15 - Chapter 5 Class 10 Arithmetic Progressions - Part 2
Ex 5.2, 15 - Chapter 5 Class 10 Arithmetic Progressions - Part 3

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Ex 5.2, 15 For what value of n, are the nth terms of two APs 63, 65, 67,… and 3, 10, 17, … equal Let’s find nth term of both APs 1st AP 63, 65, 67,… We know that an = a + (n – 1) d Here, a = 63 d = 65 – 63 = 2 Putting these in formula an = a + (n – 1) d = 63 + (n – 1) × 2 = 63 + 2n – 2 = 61 + 2n 2nd AP 3, 10, 17 … We know that an = a + (n – 1) d Here, a = 3 d = 10 – 3 = 7 Putting these in formula an = a + (n – 1) d = 3 + (n – 1) 7 = 3 + 7n – 7 = 7n – 4 Given that nth term of 1st AP = nth term of 2nd AP 61 + 2n = 7n – 4 61 + 4 = 7n – 2n 65 = 5n 65/5 = n 13 = n n = 13

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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