| $$ \begin{aligned}11c^5-9c^6+15c^5-13c^6+5c^6& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-17c^6+26c^5\end{aligned} $$ | |
| ① | Combine like terms: $$ \color{blue}{11c^5} \color{red}{-9c^6} + \color{blue}{15c^5} \color{green}{-13c^6} + \color{green}{5c^6} = \color{green}{-17c^6} + \color{blue}{26c^5} $$ |