Tap the blue circles to see an explanation.
$$ \begin{aligned}\sqrt{-124}& \xlongequal{ }\sqrt{124}\cdot i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}} \sqrt{ 4 \cdot 31 } i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}} \sqrt{ 4 } \cdot \sqrt{ 31 } i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}2\sqrt{31}i\end{aligned} $$ | |
① | Factor out the largest perfect square of 124. ( in this example we factored out $ 4 $ ) |
② | Rewrite $ \sqrt{ 4 \cdot 31 } $ as the product of two radicals. |
③ | The square root of $ 4 $ is $ 2 $. |