ISI2015-DCG-13

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For all the natural number $n \geq 3, \: n^2+1$ is

1. divisible by $3$
2. not divisible by $3$
3. divisible by $9$
4. None of these

recategorized

if we take $n=4$ then $n^2+1=17$ which is not divisible by $3$ and $9$.

So option a and c are eliminated.

Option B. is correct option.

For proof refer this

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