Thread: Restrictions on variables

For the question
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)

Look at the denominator .

If n = +1 then .
If n = -1 then .

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

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