# Math Help - Restrictions on variables

1. ## Restrictions on variables

For the question $(n^3+2n^2-n-2) / (n^2-1)$
i found the answer to be n+2 using long division

in the book the restrictions on the variable says +or - 1
i think it is just +1
could someone explain to me why the book put this (assuming that it is correct of course)

2. Look at the denominator $n^{2}-1$.

If n = +1 then $(1)^{2}-1 = 1 - 1 = 0$.
If n = -1 then $(-1)^{2} -1 = 1 - 1 = 0$.

The denominator cannot equal zero and so n cannot equal +1 or -1.

3. thanks ....i totally missed that the n was squared lol