(4) If five times the 5th term of an A.P. is equal to eight times its – InterviewSolution

1.	(4) If five times the 5th term of an A.P. is equal to eight times its 8th term, then show thatits 13th term is zero.
Answer» let first term be a and common difference be daccording to given question5 × a(5) = 8 × a(8)5(a + 4d) = = 8(a + 7d)5a + 20d = 8a + 56d3a + 36d = 0a + 12d = 0a = -12dso,a(13) = a + 12d = -12d + 12d = 0

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