Question

the sum of first n terms of an ap is 3 and square + 6 and find the nth term of this AP​

Answer 1

Answer:

6n + 3

Step-by-step explanation:

Given: Sn = 3n^2 + 6n    ...(i)

Now,

Replacing n by (n - 1) in (i), we get,

Sn - 1 = 3(n - 1)^2 + 6(n - 1)

=> 3(n^2 + 1 - 2n) + 6n - 6

=> 3n^2 + 3 - 6n + 6n - 6

=> 3n^2 - 3

nth term of the A.P. an = Sn - Sn - 1

∴ an = 3n^2 + 6n - 3n^2 + 3

        = 6n + 3

Hence, nth term of AP = 6n + 3

#Hope my answer helped you