Question 1128718
A radical is an expression that has a root, like a square root.
Basically this is a root: √a+b The √ is the radical symbol and is often just called the root sign.
:
If there is no number over the √ it is assumed that you have a square root. But you could have a 3, 4, etc The 3 is called a cube root, higher numbers go by 4th root, 5th root, etc.
: 
The number sitting on top of the √ is the radical, and the number(s) under the line to the right of it (I can't make the line here but see attachment below) are called the radicand.
*[illustration Radical.JPG]