A square root of a number *b* is the solution of the equation *x*^{2} = *b*. It is a number that when multiplied by itself gives you *b*. Every positive number *b* has two **square roots**, denoted and – . The **principal square root **of *b* is the positive square root, denoted .

**Example 1:**

The **square roots **of 25 are and since 5^{2} = 25 and (–5)^{2} = 25.

The **principal square root **of 25 is

**Example 2:**

Find the real roots of the equation *x*^{2} = 100.

Therefore the roots are 10 and –10.

**Example 3:**

Simplify

indicates the **principal **(or positive) **square root** so