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Question
Following are APs or not? If they form an A.P. find the common difference d and write three more terms:
-10, -6, -2, 2 …
Solution
−10, −6, −2, 2 …
It can be observed that
a2 − a1 = (−6) − (−10) = 4
a3 − a2 = (−2) − (−6) = 4
a4 − a3 = (2) − (−2) = 4
i.e., ak+1 − ak is same every time. Therefore, d = 4
The given numbers are in A.P.
Three more terms are
a5 = 2 + 4 = 6
a6 = 6 + 4 = 10
a7 = 10 + 4 = 14
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