$$ \begin{aligned}-14cd-2c^2d^2+15cd+8c^2d^2+15cd& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}6c^2d^2+16cd\end{aligned} $$ | |
① | Combine like terms: $$ \color{blue}{-14cd} \color{red}{-2c^2d^2} + \color{green}{15cd} + \color{red}{8c^2d^2} + \color{green}{15cd} = \color{red}{6c^2d^2} + \color{green}{16cd} $$ |