Check whether the following sequences are in A.P. (v) 1, -1, 1, -1, 1, -1,............

Check whether the following sequences are in A.P.

(v) 1, -1, 1, -1, 1, -1,............

Solution :

d = t2 - t1 d = -1 - 1 d  = -2

d = t3 - t2 d = 1 - (-1) =  1 + 1   =  2

The given sequence is not arithmetic progression.