Tap the blue circles to see an explanation.
$$ \begin{aligned}\sqrt{-162}& \xlongequal{ }\sqrt{162}\cdot i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}} \sqrt{ 81 \cdot 2 } i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}} \sqrt{ 81 } \cdot \sqrt{ 2 } i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}9\sqrt{2}i\end{aligned} $$ | |
① | Factor out the largest perfect square of 162. ( in this example we factored out $ 81 $ ) |
② | Rewrite $ \sqrt{ 81 \cdot 2 } $ as the product of two radicals. |
③ | The square root of $ 81 $ is $ 9 $. |