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Find the sum of 51 terms of the A. P. whose second term is 2 and the fourth term is 8. |
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Answer» 1,2,3,4,5,6......a+d=2 . a=2-d ................. ia+3d=8 .........iifrom i and ii2 - d +3d=82d=6d=3a= - 1S51 = 51/2(2a+ (51-1)d) = 51a+25x51x3 = 51x-1 + 3825 = 3774\xa0 a+d=2a+3d=8-d=-6d=6a+6=2a=-4 |
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