| $$ \begin{aligned}8x(6x+6)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}48x^2+48x\end{aligned} $$ | |
| ① | Multiply $ \color{blue}{8x} $ by $ \left( 6x+6\right) $ $$ \color{blue}{8x} \cdot \left( 6x+6\right) = 48x^2+48x $$ |