Which of the following sequences are in arithmetic progession ?
(i) 2,6,10,14, ........
(ii) 15,12,9,6,.........
(iii) 5,9,12,18,.......
(iv) 12,13,14,15,.....
For a sequence to be in AP
b-a=c-b
taking 1st sequence
6-2=4
10-6=4
so we can say 1st sequence is in Ap
Taking second sequence
12-15=-3
also 9-12=-3
hence 2nd sequence is also in AP
(III)
9-5=4
12-9=3
HERE B-A is not equal to C-B
so the sequence is not in AP
(iv)