Question

Following are APs or not? If they form an A.P. find the common difference d and write three more terms: 

1², 3², 5², 7² …

Answer 1

1², 3², 5², 7² …

Or, 1, 9, 25, 49 …..

It can be observed that

a₂ − a₁ = 9 − 1 = 8

a₃ − a₂ = 25 − 9 = 16

a₄ − a₃ = 49 − 25 = 24

i.e., a_k+1 − a_k is not the same every time.

Therefore, the given numbers are not in A.P.