How can I simplify this expression

[spacewater]

- (1/x) + (2 / (x²+1)) - (1/(x³+x))

I came up with x³+x+1 as LCD but when i checked the answer in the back it was wrong. Can someone elaborate this for me please?

 

[Loren]

- (1/x) + (2 / (x²+1)) - (1/(x³+x))

Denominators are x, x[sup:4ww8vgkq]2[/sup:4ww8vgkq]+1, and x(x[sup:4ww8vgkq]2[/sup:4ww8vgkq]+1).

Therefore the lcd is x(x[sup:4ww8vgkq]2[/sup:4ww8vgkq]+1).