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38. Find the nĂźmber ferm is 19, findCBSE 2013timen its sesond term. If its 5h term is 22, find the15, 218.39. The 19th term of an A. P. is equal to three times its sixth term. If its.9tthe A.Ptu |
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Answer» Let 'a' be the 1st term(a₁) and 'd' the common difference of the A.P.s. Ans1=> a₉ = 19. a+(9-1)d = 19. a+8d=19 .....(1) Now, a₁₉ = 3×a₆ a+(19-1)d=3[a+(6-1)d] a+18d=3(a+5d) simplifying, we get, a=3d/2. ......(2)Putting value of a in (1) 3d/2 + 8d=19Solving we get d=2.Putting d=2 in (1) we get a=3. |
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