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If (m+1)th term of an A.P is twice the (n+1)th term, Prove that (3m+1)th term is twice the (m+n+1)th term. |
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Answer» Given a+ md =2(a+ nd) then a = (m-2n)d t3m+1 = a +3md = (m -2n)d +3md = 4nd -2nd = 2(2m-n)n .......(1) tm+n+1 = a +(m +n)d = (m -2n)d + (m +n) d = (2m -n)d .........(2) From (1) and (2) t3m+1 = 2tm+n+1 |
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