Question

1. If the sum of n terms of an A.P. be 3n2

+ n and its common difference is 6 then its first term is​

Answer 1

Answer:first term of an A.P is 4.

Step-by-step explanation:Hi,

Given that Sum to n terms of an AP is

3n² + n

Given common difference is 6,

If suppose a is the first term of A.P and 'd' is the

common difference, the Sum to n terms of an A.P is

given by Sn = (n/2)*[2a + (n - 1)d]

Given Sn = 3n² + n

If we substitute n = 1 , in Sn we get Sum to 1 tems of an A.P

which is equivalent to first term of A.P itself,

So, 1st term of A,P = S₁ = 3.1² + 1

= 3 + 1

= 4.

Hence, first term of an A.P is 4.

Hope, it helps !

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