Chapter 4 - Quadratic Functions and Equations - Square Roots and Radicals - Exercises - Page 225: 11

$$|xy|$$

Recall: (1) $\sqrt{x^2}=|x|$ (2) $(a^mb^m)=(ab)^m$ Use rule (2) above to obtain: \begin{align*} \sqrt{x^2y^2}&=\sqrt{(xy)^2} \end{align*} Use rule (1) above to obtain: \begin{align*} \sqrt{(xy)^2}&=|xy| \end{align*}