Question

If $n$ is an odd positive integer, then $n^2-1$ is always divisible by

• A. $6$
• B. $10$
• C. $8$
• D. $16$

Answer 1

The correct option is C $8$

$n$ is odd positive integer

$n^2-1$

$=(n-1)(n+1)$

both terms are even and difference of $2$, So one is divisible by $4$ and other by $2$.

So, $4\times 2=8$

It should be divisible by $8$.