Sum of first n terms of an A.P is 2n2. Find its nth term.
4n - 4
In a sequence, we get the sum of n terms by adding nth term to the sum of (n-1)terms. We can write this as Sn=Sn−1+tn ⇒tn=Sn−S(n−1) =2n2−2(n−1)2 =2(n2−(n2−2n+1)) =2(2n−1) =4n−2
The sum of first n terms of an A.P. is 5n-n2. Find the nth term of this A.P.
If the sum of n terms of an A.P. is 2n2+5n, then its nth term is