Tap the blue circles to see an explanation.
| $$ \begin{aligned}-9\sqrt{5}+\sqrt{45}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-9\sqrt{5}+3\sqrt{5} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-6\sqrt{5}\end{aligned} $$ | |
| ① | $$ \sqrt{45} =
\sqrt{ 3 ^2 \cdot 5 } =
\sqrt{ 3 ^2 } \, \sqrt{ 5 } =
3 \sqrt{ 5 }$$ |
| ② | Combine like terms |