Answer 1

In the given problem, the sum of n terms of an A.P. is given by the expression,

S_n = 3n² + n

Here, we can find the first term by substituting n = 1 as sum of first term of the A.P. will be the same as the first term. So we get,

S_n = 3n² + n

S₁ = 3 (1)² + (1)

     = 3 +1

      = 4

Therefore, the first term of this A.P is a = 4  .