$$ \begin{aligned}4x^2(3x-5y+8z)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}12x^3-20x^2y+32x^2z\end{aligned} $$ | |
① | Multiply $ \color{blue}{4x^2} $ by $ \left( 3x-5y+8z\right) $ $$ \color{blue}{4x^2} \cdot \left( 3x-5y+8z\right) = 12x^3-20x^2y+32x^2z $$ |