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 $\sqrt{b}$ and $-\sqrt{b}$. The **principal square root **of $b$ is the positive square root, denoted $\sqrt{b}$.

**Example 1:**

The **square roots **of $25$ are $\sqrt{25}=5$ and $-\sqrt{25}=-5$ since ${5}^{2}=25$ and ${\left(-5\right)}^{2}=25$.

The **principal square root **of $25$ is $\sqrt{25}=5$.

**Example 2:**

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

$x=\pm \sqrt{100}=\pm 10$

Therefore, the roots are $10$ and $-10$.

**Example 3:**

Simplify $\sqrt{36}$.

$\sqrt{36}$ indicates the **principal **(or positive) **square root** so $\sqrt{36}=6$.