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