Tap the blue circles to see an explanation.
| $$ \begin{aligned}2\sqrt{2}-3\sqrt{18}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}2\sqrt{2}-9\sqrt{2} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-7\sqrt{2}\end{aligned} $$ | |
| ① | $$ - 3 \sqrt{18} =
-3 \sqrt{ 3 ^2 \cdot 2 } =
-3 \sqrt{ 3 ^2 } \, \sqrt{ 2 } =
-3 \cdot 3 \sqrt{ 2 } =
-9 \sqrt{ 2 } $$ |
| ② | Combine like terms |