If the sum of first M terms of an AP is 1/2(3m2+7m)write it's Mth term . Hence find its 20th term
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Sn - S (n-1) = an
So, a2 = S2 - S1
a2 = {2(2)^2 + 3 x2 } - { 2( 1)^2 + 3 x 1}
a2 = ( 8 + 6) - ( 2 + 3)
a2 = 14 - 5
a2 = 9
Therefore the 2nd term is 9
So, a2 = S2 - S1
a2 = {2(2)^2 + 3 x2 } - { 2( 1)^2 + 3 x 1}
a2 = ( 8 + 6) - ( 2 + 3)
a2 = 14 - 5
a2 = 9
Therefore the 2nd term is 9
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