Question

If the sum of n terms of an A.P. is S_n = 3n² + 5n. Write its common difference.

Answer 1

Here, we are given,

Let us take the first term as a and the common difference as d.

Now, as we know,

So, we get,

Also,

On comparing the terms containing n in (1) and (2), we get,

Therefore, the common difference is.