Show that the sequence defined by `a_n=3n^2-5` is not an A.P.

Explanation

Given, `a_n = 3n^2 – 5`


Now putting` n = 1, 2, 3, 4` we get,


` a_1 = 3(1)^2 – 5= 3 – 5 = -2 `


`a^2 = 3(2)^2 – 5 = 12 – 5 = 7`


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