Tap the blue circles to see an explanation.
$$ \begin{aligned}4\sqrt{28}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}4\cdot \sqrt{ 4 \cdot 7 } \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}4\cdot \sqrt{ 4 } \cdot \sqrt{ 7 } \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}4\cdot2 \sqrt{ 7 } \xlongequal{ } \\[1 em] & \xlongequal{ }8\sqrt{7}\end{aligned} $$ | |
① | Factor out the largest perfect square of 28. ( in this example we factored out $ 4 $ ) |
② | Rewrite $ \sqrt{ 4 \cdot 7 } $ as the product of two radicals. |
③ | The square root of $ 4 $ is $ 2 $. |