1 - n + n - 1
____ ____ = 1
n + 1 1 - n
[ 1 - n] [ 1 - n ] + [ n - 1 ] [ n + 1 ]
__________________________ = 1
[ 1 + n ] [ 1 - n ]
[ n^2 - 2n + 1 + n^2 - 1 ]
____________________ = 1
[ 1- n^2 ]
[ 2n^2 - 2n ] = 1 - n^2
3n^2 - 2n - 1 = 0 factor
(3n + 1) ( n - 1) = 0
Set each factor to 0 and solve for n and we have that
n = -1/3 or n = 1
Reject the second solution since it makes an original denominator = 0
So
n = -1 / 3