Answer
The domain of F(x) is {All real numbers, $x\ne0$}
Work Step by Step
$$F(x)= \frac{x-2}{x^{3}+x}$$
To find the domain, we first must find what values create a situation where the denominator equals 0.
$${x^{3}+x}=0$$
$$x(x^{2}+1)=0 $$
$$x\ne0,x^{2}+1\ne0$$
If we solved for $x$ in $x^{2}+1\ne0$, it would give us an imaginary number. So, we just keep $x\ne0$, and use that for our domain.