Ex 5.3, 6 - The first and last term of AP are 17 and 350 - Ex 5.3

  1. Class 10
  2. Important Questions for Exam - Class 10
Ask Download

Transcript

Ex 5.3 ,6 The first and the last term of an AP are 17 and 350 respectively. If the common difference is 9, how many terms are there and what is their sum? Given a = 17 , l = 350, d = 9 We need to find how many terms i.e. n and their sum i.e. Sn From (1) and (2) 367ร— ๐‘›/2 = ๐‘›/2 (25 + 9n) 367 = 25 + 9n 367 โ€“ 25 = 9n 342 = 9n 342/9 = n 38 = n n = 38 Now, we need to find sum Putting value of n in (1) Sum = 367 ร— ๐‘›/2 = 367 ร— 38/2 = 367 ร— 19 = 6973

About the Author

Davneet Singh's photo - Teacher, Computer Engineer, Marketer
Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.