Question 320523
3x + 1) / (x + 1) – (3x + 1) / (x – 1) 
..
LCM = (x+1)(x-1)
(3x+1)(x-1)-(3x+1)(x+1) / (x+1)(x-1)
(3x+1)(x-1-x-1) /x+1)(x-1)
-2(3x+1)/x^2-1