Tap the blue circles to see an explanation.
| $$ \begin{aligned}-2\sqrt{20}-2\sqrt{5}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-4\sqrt{5}-2\sqrt{5} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-6\sqrt{5}\end{aligned} $$ | |
| ① | $$ - 2 \sqrt{20} =
-2 \sqrt{ 2 ^2 \cdot 5 } =
-2 \sqrt{ 2 ^2 } \, \sqrt{ 5 } =
-2 \cdot 2 \sqrt{ 5 } =
-4 \sqrt{ 5 } $$ |
| ② | Combine like terms |