###### Definition8.2.1

If $$y^2=x$$ for a positive number $$y\text{,}$$ then $$y$$ is called the square root of $$x\text{,}$$ and we write $$y=\sqrt{x}\text{,}$$ where the $$\sqrt{\phantom{x}}$$ symbol is called the radical or the root. We call expressions with a root symbol radical expressions. The number inside the radical is called the radicand.

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