If $\lim _{x \rightarrow c} f(x)$ exists and if $n \geq 2$ is an integer, then $ \lim _{x \rightarrow c} \sqrt[n]{f(x)}=\sqrt[n]{\lim _{x \rightarrow c} f(x)} $ provided $f(x) \geq 0$ if $n$ is even.