Question

If the sum of n terms of an A.P. be 3n² + n and its common difference is 6, then its first term is

(a) 2

(b) 3

(c) 1

(d) 4

Answer 1

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

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

Therefore, the first term of this A.P is. So, the correct option is (d).