n 1 m - -- + m*n + - 2 m m
1 n m + - + m*n - -- m 2 m
m + 1/m + m*n - n/m^2
2 / 3 3\ m + m*\m - n + n*m / ---------------------- 3 m
3 3 m + m - n + n*m ----------------- 2 m
3 m - n + m *(1 + n) ------------------ 2 m
m - n m + m*n + ----- 2 m