If r² = x, then 'r' is called the square root of 'x'.

It is written as x^1/2 or, more commonly as .

The square root of x, when written in the form x^1/2 or , is called radicalor surd.

Therefore, the square root is the n^th root of a number with n = 2.

Any positive real number has two square roots: positive and negative.

The positive square root is the principal square root or the square root.

If the negative square root has to be considered, it has to be mentioned specifically.

Thus we have

= 4

– = – 4

is not defined.

The square root function is the inverse function of

f(x) = x²   for x ≥ 0

The graph of x vs is shown below.