Justify whether it is true to say that the following are the nth terms of an AP.
Put n = 1, 2, 3, 4
We get
a1 = 3(1)2 + 5 = 8
a2 = 3(2)2 + 5 = 17
a3 = 3(3)2 + 5 = 32
a4 = 3(4)2 + 5 = 53
List of AP is 8, 17, 32, 53. . . .
a2 - a1 = 17 - 8 = 9
a3 - a2 = 32 - 17 = 15
As
a3 - a2 is not equal to a2 - a1
the list is not an AP
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