**Find principal roots**

If *n *is even, positive numbers have two *n*th roots.For example, both 4 and -4 are square roots of 16, and 2 and -2 are fourth roots of 16. In such cases, the notation represents the positive root, called the **principal root.**

* *

*n***th Root**

If *n *is ** even **and

*a*is

**or 0, then**

*positive* represents the principal *n*th root of *a*, and

– represents the negative *n*th root of *a*.

If *n *is ** even **and

*a*is

**then**

*negative,*is not a real number.

If *n *is ** odd, **then

there is exactly one *n*th root of *a*, written

If *n *is even, then the two *n*th roots of *a *are often written together as

,with read “positive or negative.”.