If 7 times the seventh term of the AP is equal to 5 times of the fifth term, then find the value of its 12 th term.

This question is similar to Question 12 or 2nd CBSE Class 10 Sample Paper 2020 Boards

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Question 1 – Choice 2

If 7 times the seventh term of the AP is equal to 5 times the fifth term, then find the value of its 12th term.


Transcript

Question 1 – Choice 2 If 7 times the seventh term of the AP is equal to 5 times the fifth term, then find the value of its 12th term. We know that an = a + (n – 1)d Given that 7 times the 7th term is equal to 5 times its 5th term 7 × a7 = 5 × a5 7 × (a + (7 – 1)d) = 5 × (a + (5 – 1)d) 7 × (a + 6d) = 5 × (a + 4d) 7a + 42d = 5a + 20d 7a – 5a = 20d – 42d 2a = −22d a = (−22𝑑)/2 a = –11d Now, we need to find the 12th term a12 = a + (12 – 1)d = a + 11d Putting a = –11d = –11d + 11d = 0 So, 12th term is 0

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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, Social Science, Physics, Chemistry, Computer Science at Teachoo.