In many cases, some numbers have more than one realnth root. For example, 9 has two square roots, 3 and -3.
In this case, the principal root of 9 is the positive root 3, since it has the same sign as 9. In general, the principal nth root of a number a is the nth root that has the same sign as a. It is denoted by the radical symbol and n is the index of the radical.
A special case is when n is and odd number and b is negative. In this situation, there will be no nonnegative root and the principal root is negative. Some examples of nth roots and its description can be seen below.
16 indicates the principal square root of 16.
-16 indicates the opposite of the principal square root of 16.
±16 indicates both square roots of 16.
3-125 indicates the principal cube root of -125.
5-243 indicates the principal fifth root of -243.