$$ \begin{aligned}5\sqrt{225}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}5\cdot15 \xlongequal{ } \\[1 em] & \xlongequal{ }75\end{aligned} $$ | |
① | The square root of $ 225 $ is $ 15 $. |