Find the arithmetic mean of :

(i) -5 and 41

(ii) 3x - 2y and 3x + 2y

(iii) (m + n)² and (m - n)²

Find the sum of first 20 terms of an A.P. whose first term is 3 and the last term is 57.

The n^th term of sequence is 8 - 5n. Show that the sequence is an A.P.

Find the general term (n^th term) and 23^rd term of the sequence, 3, 1, -1, -3, ………