Question

Question 4 (ix)
Which of the following are APs? If they form an A.P. Find the common difference d and write three more terms.
(ix) 1, 3, 9, 27, …

Answer 1

If the difference between any two consecutive terms of a series is a constant value, then the series is an A.P.

Given, the series is :
$1,3,9,27,\dots$
Here,
$a_2-a_1=3-1=2a_3-a_2=9-3=6a_4-a_3=27-9=18$

Note that the difference between any two consecutive terms of the series is not a constant value.
Hence, the given series is not an AP.