Ex 5.3, 3 - Chapter 5 Class 10 Arithmetic Progressions - Part 17

Ex 5.3, 3 - Chapter 5 Class 10 Arithmetic Progressions - Part 18

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

Transcript

Ex 5.3, 3 In an AP (vii) Given a = 8, an = 62, Sn = 210, find n and d. Given a = 8, an = 62, Sn = 210, Since there are n terms, ๐‘™ = an = 62 We use the formula Sn = ๐’/๐Ÿ (๐’‚+๐’) Putting a = 8, Sn = 210, ๐‘™ = an = 62 210 = ๐‘›/2 (8+62) 210 ร— 2=๐‘› ร— (70) 420 = n ร— 70 420/70=๐‘› 6 = n n = 6 Now we need to find d We can use formula an = a + (n โ€“ 1) d Putting an = 62, a = 8, n = 6 62 = 8 + (6 โ€“ 1) ร— ๐‘‘ 62 = 8 + 5d 62 โ€“ 8 = 5d 54 = 5d d = ๐Ÿ“๐Ÿ’/๐Ÿ“

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 10 years. He provides courses for Maths and Science at Teachoo.