Worked Example 1
The sum of the first $n$ terms of a sequence is given by ${{S}_{n}}=2{{n}^{2}}+n$. Prove that the series in an arithmetic series and state the common difference.
The sum of the first $n$ terms of a sequence is given by ${{S}_{n}}=2{{n}^{2}}+n$. Prove that the series in an arithmetic series and state the common difference.