| $$ \begin{aligned}2x^2(x+2)-3x& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}2x^3+4x^2-3x\end{aligned} $$ | |
| ① | Multiply $ \color{blue}{2x^2} $ by $ \left( x+2\right) $ $$ \color{blue}{2x^2} \cdot \left( x+2\right) = 2x^3+4x^2 $$ |