Answer:
When we have something like:
[tex]\sqrt[n]{x}[/tex]
It is called the n-th root of x.
Where x is called the radicand, and n is called the index.
Then the term:
[tex]\sqrt[4]{16}[/tex]
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:
[tex]\sqrt[4]{16} = \sqrt[4]{4*4} = \sqrt[4]{2*2*2*2} = 2[/tex]
The 4th root of 16 is equal to 2.
