Tap the blue circles to see an explanation.
$$ \begin{aligned}\sqrt{8}\cdot\sqrt{40}& \xlongequal{ }\sqrt{320} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}} \sqrt{ 64 \cdot 5 } \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}} \sqrt{ 64 } \cdot \sqrt{ 5 } \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}8\sqrt{5}\end{aligned} $$ | |
① | Factor out the largest perfect square of 320. ( in this example we factored out $ 64 $ ) |
② | Rewrite $ \sqrt{ 64 \cdot 5 } $ as the product of two radicals. |
③ | The square root of $ 64 $ is $ 8 $. |