the sum from 2 to infinity of 2/(n^2 - 1)

so first i factor the denominator

2/((n + 1)(n - 1))

this can expressed with partial fractions

2/((n + 1)(n - 1)) = A/(n + 1) + B/(n - 1)

which can be rearanged to

2 = A(n + 1)(n - 1) + B(n + 1)(n - 1)

now I'm stuck. I have one equation and 2 variables. I know there is something I'm forgetting how to do this.