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For an arithmetic sequence, a26=80. If the common difference is 1, find: a1= the sum of the first 43 terms= |
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Answer» Step-by-step explanation: TN = a + (n-1) dT26 = 80 d= 1 80= a + (26-1)*1 80 = a + 25 a = 80-25 a = 55 a1 = 55 Sn = 1/2{2a + (n-1)d}S43 = 1/2 {2*55 + (43-1)*1} = 1/2 (110 + 42) = 55 + 21 = 76 S43 = 76 I hope it is helpful for you..!! THANK you!! |
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