| $$ \begin{aligned}17-3^2+2s^2-5s^3+5& \xlongequal{ }17-9+2s^2-5s^3+5 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-5s^3+2s^2+13\end{aligned} $$ | |
| ① | Combine like terms: $$ \color{blue}{17} \color{red}{-9} +2s^2-5s^3+ \color{red}{5} = -5s^3+2s^2+ \color{red}{13} $$ |