# How do you find the domain of square root of 25-x^2?

The domain of $\left(\sqrt{25} - {x}^{2}\right)$ is all Real values (or all Complex numbers, if you are working in the Complex plane)
$\sqrt{25} - {x}^{2}$ is valid for all possible Real values of $x$; therefore its domain is all Real values.
Possibly the intention of this question is to determine if you recognize the difference between domain and range. The range is the set of values that the expression can have (in this case, the range is all Real values $\le 5$).