A series has An =n×n +1is this AP or not

1.	A series has An =n×n +1is this AP or not
Answer» an = n2 - 1Put n = 1, 2, 3, 4, ..... we get,a1 = 12 - 1 = 1 - 1 = 0a2 = 22 - 1 = 4\xa0- 1 = 3a3 = 32 - 1 = 9 - 1 = 8a4 = 42 - 1 = 16 - 1 = 15, and so on.Hence, the given sequence is 0, 3, 8, 15a2 - a1 = 3 - 0 = 3a3 - a2 = 8 - 3 = 5As a2 - a1\xa0{tex} \\ne {/tex}\xa0a3 - a2, the given sequence is not an AP.

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