1. Chapter 5 Class 10 Arithmetic Progressions (Term 2)
  2. Serial order wise
  3. Ex 5.3

Ex 5.3, 13 - Chapter 5 Class 10 Arithmetic Progressions (Term 2)

Last updated at March 22, 2021 by

Find the sum of first 15 multiples of 8? [with Video] - Teachoo

Ex 5.3, 13 - Chapter 5 Class 10 Arithmetic Progressions - Part 2

  1. Chapter 5 Class 10 Arithmetic Progressions (Term 2)
  2. Serial order wise

    3. Ex 5.3

    Examples →

Transcript

Ex 5.3, 13 Find the sum of first 15 multiples of 8. Multiples of 8 are 8, 16, 24,โ€ฆ Since difference is same, it is an AP We need to find sum of first 15 multiples We use formula Sn = ๐‘›/2 (2๐‘Ž+(๐‘›โˆ’1)๐‘‘) Here, n = 15, a = 8 & d = 16 โ€“ 8 = 8 Putting values in formula Sn = ๐’/๐Ÿ (๐Ÿ๐’‚+(๐’โˆ’๐Ÿ)๐’…) = 15/2(2 ร— 8+(15โˆ’1) ร— 8) = 15/2 (16+14 ร— 8) = 15/2 (16+112) = 15/2 ร— 128 = 960 Therefore, the sum of first 15 multiples of 8 is 960

Chapter 5 Class 10 Arithmetic Progressions (Term 2)
Serial order wise

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