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