Answer:
When we have something like:
![\sqrt[n]{x}](https://img.qammunity.org/2022/formulas/mathematics/high-school/ystkim2l19uq2hi8jihuiokmvelgmrz0v2.png)
It is called the n-th root of x.
Where x is called the radicand, and n is called the index.
Then the term:
![\sqrt[4]{16}](https://img.qammunity.org/2022/formulas/mathematics/college/9mpk7s79jc4t9eac7jwnia45neqzsjrzwz.png)
is called the fourth root of 16.
And in this case, we can see that the index is 4, and the radicand is 16.
At the end, we have the question: what is the 4th root of 16?
this is:
![\sqrt[4]{16} = \sqrt[4]{4*4} = \sqrt[4]{2*2*2*2} = 2](https://img.qammunity.org/2022/formulas/mathematics/high-school/ozxu6x9j81nq0uh85z206djdjej86nwngd.png)
The 4th root of 16 is equal to 2.