If “a” is any non-negative number than its square root is any non-negative number whose square is “a“. We write the square root of n as √n. Roots are also referred to as radicals. A square root is never a negative number. If we are speaking of a negative square root of 9 for example we would write is like: -√9.
The cube root of a real number “a” is the number whose cube is a. The cube root of a is written as “3√a”.
The fourth root of the non-negative number a is defined as the non-negative number whose fourth power is a and written as “4√a”.