Given the first n terms of the sequence {an} and Sn = n ^ 2 + 2n (1), find the general term formula of the sequence {an} (2), find the 10th term of the sequence

Given the first n terms of the sequence {an} and Sn = n ^ 2 + 2n (1), find the general term formula of the sequence {an} (2), find the 10th term of the sequence

solution
(1) General term an = sn-sn-1 = n ^ 2 + 2n - [(n-1) ^ 2 + 2 (n-1)] = 2n + 1
(2) The 10th term of sequence A10 = 2 * 10 + 1 = 21