$$ \begin{aligned}2u(2x+5)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}4ux+10u\end{aligned} $$ | |
① | Multiply $ \color{blue}{2u} $ by $ \left( 2x+5\right) $ $$ \color{blue}{2u} \cdot \left( 2x+5\right) = 4ux+10u $$ |