Sometimes
1. The radical expression [tex] \sqrt[n]{} [/tex] with even n requires a variable with positive quantity. For example, if you have [tex] \sqrt[4]{x^3} [/tex], then always [tex]x^3\ge 0[/tex].
2. If you have radical expression [tex] \sqrt[n]{} [/tex] with odd n, ia variable may be arbitrary. For example, for [tex] \sqrt[7]{x} [/tex] you can consider all real x.
