>>762
1/{x+(x/(x^2-1))} という意味であれば

{x+(x/(x^2-1))} = { x(x^2 -1) +x}/(x^2 -1) = (x^3)/(x^2 -1)
だから

1/{x+(x/(x^2-1))} = (x^2 -1)/(x^3)