Square root
A square root of a number 
is a number 
such that 
. Generally, the square root only takes the positive value of . This can be altered by placing a 
before the root. Thus is a square root of if is the square of .
Notation
The square root (or the principle square root) of a number is denoted 
. For instance, 
. When we consider only positive reals, the square root function is the inverse of the squaring function.
