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Question 8 (Or 2nd) - CBSE Class 10 Sample Paper for 2019 Boards - Solutions of Sample Papers for Class 10 Boards

Last updated at Dec. 16, 2024 by Teachoo

Question 8 (OR 2 nd   question)

If 7 times the 7 th term of an A.P is equal to 11 times its 11 th term, then find its 18th term.

Transcript

Question 8 (OR 2nd question) If 7 times the 7th term of an A.P is equal to 11 times its 11th term, then find its 18th term. We know that an = a + (n – 1)d Given that 7 times the 7th term is equal to 11 times its 11th term 7 × a7 = 11 × a11 7 × (a + (7 – 1)d) = 11 × (a + (11 – 1)d) 7 × (a + 6d) = 11 × (a + 10d) 7a + 42d = 11a + 110d 7a – 11a = 110d – 42d –4a = 68d a = 68𝑑/(−4) a = –17d Now, we need to find the 18th term a18 = a + (18 – 1)d = a + 17d Putting a = –17d = –17d + 17d = 0 So, 18th term is 0
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Davneet Singh

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