| $$ \begin{aligned}x^2-11x+18+x-2& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}x^2-10x+16\end{aligned} $$ | |
| ① | Combine like terms: $$ x^2 \color{blue}{-11x} + \color{red}{18} + \color{blue}{x} \color{red}{-2} = x^2 \color{blue}{-10x} + \color{red}{16} $$ |