1.

If the sum of first m terms of an AP is (2m2 + 3m) then what is its second term?

Answer»

Sum of first m terms of an AP = 2m2 + 3m (given)

Sm = 2m2 + 3m

Sum of one term = S1 = 2(1)2 + 3 x 1 = 2 + 3 = 5 = first term

Sum of first two terms = S2 = 2(2)2 + 3 x 2 = 8 + 6=14

Sum of first three terms = S3 = 2(3)2 + 3 x 3 = 18 + 9 = 27

Now,

Second term = a2 = S2 – S1 = 14 – 5 = 9



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