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If in an A.P., and , where denotes the sum of r terms of the A.P., then is equal to

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If the first, second and last term of an A.P. are a, b and 2a respectively, then its sum is

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If, is the sum of an arithmetic progression of ‘n’ odd number of terms and the sum of the terms of the series in odd places, then

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If in an A.P., the pth term is q and term is zero, then the term is

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The 10^th common term between the A.P.s 3, 7, 11, 15, ... and 1, 6, 11, 16, ... is