Nested radical

In algebra, a nested radical is a radical expression (one containing a square root sign, cube root sign, etc.) that contains (nests) another radical expression. Examples include

$${\displaystyle {\sqrt {5-2{\sqrt {5}}\ }},}$$

which arises in discussing the regular pentagon, and more complicated ones such as

$${\displaystyle {\sqrt[{3}]{2+{\sqrt {3}}+{\sqrt[{3}]{4}}\ }}.}$$