Scoaterea factorilor de sub radical

$$\begin{gathered} a, b\in \mathrm{ℝ}, b\ge 0 \\ \sqrt{a^{2}b}=\left|a\right|\sqrt{b}=\left\{\begin{array}{l} a\sqrt{b}, a\ge 0\\ -a\sqrt{b}, a<0\end{array}\right. \end{gathered}$$

Exemple:

$$\begin{gathered} \sqrt{2^2·5}=2\sqrt{5} \\ \sqrt{{\left(-3\right)}^2·7}=\left|-3\right|\sqrt{7}=3\sqrt{7} \\ \sqrt{72}=\sqrt{2^3·3^2}=\sqrt{2^2·3^2·2}=\left(2·3\right)\sqrt{2}=6\sqrt{2}. \end{gathered}$$