Question

which of the following is not an AP
??

2,2,2,2
10,7,4
23,21,1
2,7,12

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Answer 1

Answer:

1 and 3 were not AP BECAUSE there is no common difference between them

Answer 2

23, 21, 1 is not an A.P because the difference between two consecutive numbers is not the same always.
( Since, 21 - 23 is not equal to 1 - 21 )