Tap the blue circles to see an explanation.
$$ \begin{aligned}\sqrt{-54}& \xlongequal{ }\sqrt{54}\cdot i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}} \sqrt{ 9 \cdot 6 } i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}} \sqrt{ 9 } \cdot \sqrt{ 6 } i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}3\sqrt{6}i\end{aligned} $$ | |
① | Factor out the largest perfect square of 54. ( in this example we factored out $ 9 $ ) |
② | Rewrite $ \sqrt{ 9 \cdot 6 } $ as the product of two radicals. |
③ | The square root of $ 9 $ is $ 3 $. |