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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:
0, -4, -8, -12, …
Solution
0, −4, −8, −12 …
It can be observed that
a2 − a1 = (−4) − 0 = −4
a3 − a2 = (−8) − (−4) = −4
a4 − a3 = (−12) − (−8) = −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 = − 12 − 4 = −16
a6 = − 16 − 4 = −20
a7 = − 20 − 4 = −24
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