what is the 4 called

Answer:
The Index
Step-by-step explanation:
A radical expression is composed of three parts:
The Radicand - The number or term under the horizontal bar of the radical symbol.
Radical Symbol - The Radical Symbol √
Index - The number near the "check" part of the radical symbol.
In the given expression, 4 is the index. We are supposed to find the 4th root of x to the third power.
Hope this helps.