Answer
$\left\{x|x\ge0\right\}$
Work Step by Step
The denominator of a rational expression cannot be zero so $x$ should not be equal to $-1$.
The square root is only defined when the radicand (number or expression inside a radical sign) is non-negative.
Thus, to find the numbers for which $\sqrt{2x}$ is defined, solve the inequality $2x \ge 0$ to obtain:
$2x \ge 0
\\\frac{2x}{2} \ge \frac{0}{2}
\\x \ge 0$
Having $x\ne -1$ and $x \ge 0$ mean that the domain of the give expression is any real number greater than or equal to 0.