__X+1____-__x-1____

x-1 x+1

If that means

(x+1)/(x-1) - (x-1)/(x+1) then we have

[(x+1)^2 - (x-1)^2]/(x^2-1)
= [(x^2 + 2x + 1 - (x^2 - 2x + 1)]/(x^2-1)
= 4x/(x^2-1)