| $$ \begin{aligned}2a^2+5ab-6b^2+8b^2-10ab& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}2a^2-5ab+2b^2\end{aligned} $$ | |
| ① | Combine like terms: $$ 2a^2+ \color{blue}{5ab} \color{red}{-6b^2} + \color{red}{8b^2} \color{blue}{-10ab} = 2a^2 \color{blue}{-5ab} + \color{red}{2b^2} $$ |