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

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

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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, 𝑙 = an = 62 We use the formula Sn = 𝒏/𝟐 (𝒂+𝒍) Putting a = 8, Sn = 210, 𝑙 = an = 62 210 = 𝑛/2 (8+62) 210 Γ— 2=𝑛 Γ— (70) 420 = n Γ— 70 420/70=𝑛 6 = n n = 6 Now we need to find d We can use formula an = a + (n – 1) d Putting an = 62, a = 8, n = 6 62 = 8 + (6 – 1) Γ— 𝑑 62 = 8 + 5d 62 – 8 = 5d 54 = 5d d = πŸ“πŸ’/πŸ“

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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.